Operates on in memory(data needs to be loaded from disk to memory). Swift and Objective-C iOS isn’t just about Swift. However, don’t mix up Core Data with database. If you are familiar with Oracle or MySQL, you know that relational database stores data in the form of table, row and column, and it usually facilitates access through what-so-called SQL query. SQLite is database itself like we have SQL Server. A small guide to help those looking to hire a developer or designer for iOS work. What is Cocoa and Cocoa Touch? Can the NSPersistentStoreCoordinator have more persistent stores? iOS Interview Questions For Senior Developers 12 December 2015 on iOS, Interviews. As you will see during this or future posts, English it’s not my first language, so please if you are sensitive to grammatical crimes this is the best time for you to response on that, I ‘ll Correct as Soon. 18. This is an update of my two-year-old blog post on iOS interview questions.I revised it after doing extensive research while working on my book on the topic: The iOS Interview Guide. Here are the top 19 sample iOS interview questions and their answers. These groups of objects are referred to as object graphs. ... How to make a Core Data attribute unique using constraints. Don’t have Data Constraints if required need to implement by business logic. These are the basic questions generally asked in Core data 1. The big day is coming up. It speeds up the process of interaction as we don’t have to Write Queries, just work with ORM and let ORM handled the backend. ❍ The NSManagedObjectModel object knows about the data model by loading one or more data model files during its initialization. Core data is an object graph manager which also has the ability to persist object graphs to the persistent store on a disk. The NSManagedObjectContext object manages a collection of model objects, instances of the NSManagedObject class. It is possible for an application to have multiple managed object contexts. The Core Data framework excels at managing complex object graphs. Every managed object context posts three types of notifications to notify objects about the changes taking place in the managed object context: NSManagedObjectContextObjectsDidChangeNotification, NSManagedObjectContextWillSaveNotification, NSManagedObjectContextDidSaveNotification. The technique is known as Uniquing. Menu iOS Interview Questions for Senior Developers in 2017 17 September 2017 on iOS, Interviews, Interview Questions, Swift. It also suits a business requirement where you have a model with it’s attributes. For example:- in the Employee entity, you could define Person as an abstract entity and specify that only concrete sub-entities (Employee and Customer) can be instantiated. get me on:- @Ravindra Bhati, Functional Tests for Docker Microservices, Python Code to Find Total Number of Magic Squares of Order 3 and 4, How to Get the Execution Time of a Script. 16. 4. Microsoft Power BI SQL Tableau Business Analysis Business Intelligence Data Analysis MySQL Data Modeling DAX. Search Your Question. Thanks for reading. Swift is only four years old, but it’s already become the default language for iOS development. It's the Model in the Model-View-Controller pattern that permeates the iOS SDK. https://harsivo.com/Here i have covered 15 iOS interview questions and answers. 3. Ans : When you initialise a Core Data stack, one of the steps involved is adding a store to the persistent store coordinator. Welcome to iosdose Register Now! Whereas adapters synchronize information through an existing, general-purpose interface such as REST, synchronizers use a more direct protocol, offering better integration and performance at the expense of portability and generality. The model is a collection of entity description objects(instance of NSEntityDescription). An app stays in this state briefly as it transitions to a different state. ... in Swift -iOS 8. ... use Swift along with Objective-C for now and move to pure Swift down the road in several years when it and the ecosystem of libraries around it matures enough. NSManagedObjectContext has perform(_:) and performAndWait(_:) to direct work to the correct queue. What is NSPersistentStoreCoordinator? What is the difference between transformable and binary data? Core-Data Interview Questions And Answers. They shouldn’t be initialized in one thread and accessed from a different thread. Wrapper libraries provide some much needed syntactic sugar and convenience methods to Core Data’s verbose and complicated APIs. iOS Domain is pretty enormous and deep. 17. Jobs That’s why you get the error that mentions this method — it’s trying to call the method on your class, but that method doesn’t exist. Podcast 303: What would you pay for /dev/null as a service? The questions will give you an idea about the pattern and the right way to answer the questions that may be thrown your way during the interview In Core Data, relationships between two entities are called to-one relationships, while those between one and many entities are called to-many relationships. How you can add column in entity in core data that can be also added in next release? You can think of a persistent store like a database data file where individual records each hold the last-saved values of a managed object. 32. So, if you used a transformable attribute you could read and write UIImage while still keeping NSData in the data store. How we can do multithreading with core data? With a transformable attribute, you read and write instances of any class that can be converted to and from NSData. In OS X v10.7 and later and iOS v5.0 and later, when you create a context you can specify the concurrency pattern with which you will use it using initWithConcurrencyType:. I hope you will like this. Core Data is a framework that is used to manage model layer objects. Yes, but can’t create relationships between objects in different stores. Core Data isn't the database of your application nor is it an API for persisting data to a database. Core Data abstracts the details of mapping your objects to a store, making it easy to save data from Swift and Objective-C without administering a database … The Overflow Blog Want to teach your kids to code? Core data API is provided by apple for persisting data in SQL, XML, file system. We can use the NSFetchRequest class’s property “setPropertiesToFetch”. They are calculated at runtime, usually on the basis of other property Values. How to Save custom class into Core data? In the fast-paced environment of Swift and iOS development, chances are you could be preparing for a technical interview. We need NSManagedObject, NSManagedObjectContext and a Persistence store container. This is because NSManagedObjectContext and NSManagedObject, the two most fundamental objects in Core Data, is not thread-safe. Managed object context can contain one or more managed object model instances. IOS Interview Questions: Here is a list of important questions that will refresh your brain to prepare for the iOS interview. ♥♥️♥️When you retrieve an object from an NSManagedObjectContext (MOC) you can’t tell (in the normal course of its use) whether it’s a fault or a realized object*** — Yes we can, use –isFault. There are two concurrency types a managed object context can use:-. By marking an entity as abstract in the Entity pane of the Data Model inspector, you are informing Core Data that it will never be instantiated directly. So, You Want to Scan a Billion Files in a Day. The NSManagedObjectContextObjectsDidChangeNotification notification is broadcast every time a managed object in the managed object context changes. Some of them I learned from my own experience and most of them either from senior colleagues or other online resources (Attributions added to the end).Based on this knowledge I have compiled a list of interview questions one can use to prepare while applying for the job of iOS … Persistence store coordinator communicates between managed object context and store. The awakeFromFetch is where you would add the observers when fetching. Core Data ensures that — in a given managed object context — an entry in a persistent store is associated with only one managed object. So, to ease the stress you did some prep work- completed the homework on the company you are interviewing with, stalked the hiring manager and half of the engineering team at the company of your choice on linkedin & github, you brushed up on some of the skills and knowledge you haven’t used in a while- you are ready to go. What is Managed Object Context? 6. 14. A. Interview questions for testing anti virus software for apple products. 15 Will you ever pass a managed object from one context to another context? Concurrency is the ability to work with the data on more than one queue at the same time. We have taken full care to give the top answers to all the questions. Can we do Multithreading with core data? That’s right. An NSManagedObject is a run-time representation of a Core Data entity. If you are looking for iOS Development interview questions for the beginner or experienced, then this is the right place. The interview questions as flash card sets according to topic. For the most part, AppKit and UIKit are not thread-safe. This technique project is going to explore Core Data in more detail, starting with a summary of some basic techniques then building up to tackling some more complex problems. Identifiers contain the information needed to exactly describe an object in a persistent store (like the primary key in the database), although the detailed information is not exposed. 21. The image Data is Converted to and From an NSData Instance that contains the image’s PNG Representation .this is all handled transparently for you by a custom NSValueTransformer. This factor in the design of the SQLite persistent store can create a performance issue. Data operations like insert, update and delete are performed in managed object context. In a relational database, an entity corresponds to a table. It provides generalized and automated solutions to common tasks associated with object life cycle and object graph management, including persistence. What is lazy initialization, how does this relate to core data, situations when this can be handy? ... With more than 170 iOS 11 & Swift 4 interview questions, the 170+ iOS 11 & Swift 4 Interview Questions course is here to help you. What types of stores does core data support? To fetch the data asynchronously in a background queue, Core Data provides the object NSAsynchronousFetchRequest. It is not same as SQLite which involves disk I/O (input/output) operations. I am an IOS developer, a self-taught one, a lot of curiosity and passion for coding. Core Data is a framework that … Core Data is one of the most popular frameworks provided by Apple for iOS and macOS apps. In a database, an attribute corresponds to a particular field in a table. ... Now for the important part: go to the the iOS simulator, then choose the Hardware menu and Erase All Content And Settings. ❍ it contains information about the models or entities of the object graph, what attributes they have, and how they relate to one another. We can do multithreading in core data with multiple contexts, example background context for long-running tasks (batch inserting/fetching/updating) and update UI on the main thread. In this case you create a subclass of NSValueTransformer that performs the transformation. Here is the list of most frequently asked iOS Interview Questions and Answers in technical interviews. The whole information is built is understandable way, waiting for you to take it now! While this is not the whole-database decryption that you’re looking for, it will have a much lower memory footprint than decrypting an entire database into memory. What is Latest Version of iOS & Swift ? You typically make an entity abstract if you have a number of entities that all represent specializations of (inherit from) a common entity that should not itself be instantiated. You configure this on the attribute, either in the Core Data model editor or in code. One wrong answer during your first interviews can determine if you get the job, or just a “thank you for participate”. Transient properties are properties on an NSManagedObject that are not persisted t the object-store. Here are three apps that can help. Core Data is a framework that manages an object graph. ; Inactive state: when the app is running in the foreground but is currently not receiving events. An object graph is a view of an object systemat a particular point in time. Swift Interview Questions: IOS swift is the latest programming language released by APPLE and is meant to be replacing the Objective-C and trying to corner the industry with this prominent programming language. Contribute to dmyma/iOS-interview development by creating an account on GitHub. Interview Questions And Answers - Core Data, Collection of interview questions for core data. In macOS in particular, Cocoa bindings and controllers are not threadsafe — if you are using these technologies, multithreading may be complex. The managed object context performing the save operation posts an NSManagedObjectContextDidSaveNotification notification after successfully saving its changes. Except, UIImage can’t be saved in Core Data. Any UI operation, such as creating the fetched results controller for the table view, must use a context of this type. To give a super boost to your career, below is a list of regularly posted iOS interview questions which helps in passing the IOS job interview. How to read only a few attributes of an entity? Interview Questions Interactive Review Test your Swift Find a Job Store. What you just did was completely reset the state of the iOS Simulator. Here are the top 19 sample iOS interview questions and their answers. Support for Swift: Xcode 6 explicitly supports the Swift code, it is very simple and easy to make a brand new app using 100% swift code to existing frameworks. Due to lazy keyword the object will be initialized only when accessed. In Swift, the classes are not inherited from the base class and the classes that you define without specifying its superclass, automatically becomes the base-class. An attribute is a piece of information attached to a particular entity. But UIImage can be converted to and from NSData. Core Data can then manage object instances at runtime to provide the following features. Transformable properties like this are very easy to use because you read and write to them as normal, while the encryption/decryption goes on behind the scenes. For example:- a Manager can have a to-many relationship with a set of employees, whereas an individual Employee will usually have a to-one relationship with his manager. 31. * Helpers for fetching and deleting Core Data objects using generics. Top iOS Interview Questions and Answers Blog of developers, running by developers and made for developers. “When you retrieve an object from an NSManagedObjectContext (MOC) you can’t tell (in the normal course of its use) whether it’s a fault or a realized object”. For example:- to insert a new managed object into a managed object context, it’s a class method. I will come back with more questions and answers. It mediates between the persistent store(s) and the managed object context(s) and also takes care of loading and caching data. However, if you have already given an iOS interview, or have more questions, we encourage you to add them in the comments tab below. An abstract object (in programming) or entity (in Core Data) is an object or entity that is never instantiated. Swift is a fantastic way to develop software, it is an interactive programing language which is fast, safe, and friendly to new programs. There has never been a better time to become an iOS developer. 5. As Swift has evolved to version 5.0, it’s turned into a complex and powerful language embracing both object-oriented and functional paradigms. Apple iOS Swift technical job interview questions of various companies and by job positions. It is memory efficient technique used with some of the classes like DateFormatter, Calendar also. Importantly though, when unit testing, you don’t want to use that persistent data. Contexts and their managed objects must only be accessed from the correct queue. Swift is only four years old, but it’s already become the default language for iOS development. In iOS, Apple provides UIView as a base class for all _View_s, UIViewController is provided to support the Controller which can listen to events in a View and update the View when data changes. Do you have experience in swift/java?Having hands-on experience in iOS development, Automation and Manual testing will be helpful to gain edge in career path. A great self-test if you're looking to keep current or practice for your own interview. You can treat Core Data as a framework to save, track, modify and filter the data within iOS apps, however, Core Data is not a Database. 19. An object persists data to disk and ensures the persistent store(s) and the data model are compatible. Is Core Data == SQLite or some wrapper? When it is necessary to hand off a managed object reference from one queue to another, it must be done through NSManagedObjectID instances. It defines the core components of an iOS application, from labels and buttons to table views and navigation controllers. A managed object ID uniquely identifies the same managed object both between managed object contexts in a single application, and in multiple applications (as in distributed systems). In this case, Core Data will attempt to call encodeWithCoder: on your object to convert it to NSData. A data model is a description of the data you want Core Data to store, and is a bit like creating a class in Swift: you define entities (like classes) and give them attributes (like properties). Core Data uses thread (or serialized queue) confinement to protect managed objects and managed object contexts. What is the minimum necessary classes and the relationship between them? Swift and Objective-C. 34. We have created a list of top frequently-asked iOS interview questions that will help you ace your iOS job interview. According to the Core Data concurrency rule, each thread must have its own managed object context. Object-oriented applications contain complex webs of interrelated objects. Core data is used to manage the model layer object in our application. 12. Core Data consist of following stack objects: 5. 39. what is the Difference between core data and SQLite? A controller that you use to manage the results of a Core Data fetch request and display data to the user in UITableView. Top 18 iOS Developer Interview Questions & Answers: XCode & Swift Top 25 Objective C Interview Questions & Answers Top 50 Array Interview Questions & Answers Top 17 Haskell Interview Questions & Answers An object graph is nothing more than a collection of objects that are connected with one another. What is ManagedObject 2. In this case, your class must conform to NSCoding for the transformation to occur. Swift Interview Questions: IOS swift is the latest programming language. An asynchronous fetch allows developers to execute a fetch request without blocking the Managed Object Context for the duration of the fetch. How can I encrypt Core-Data contents on an iPhone? An Entity can be abstract, in which case it is never directly attached to a managed object. If you are preparing for iOS Development with Swift 2 job interview, we will help you in clearing the interview through Wisdomjobs interview questions and answers page. All entities that inherit from another entity exist within the same table in SQLite. A fault will be converted into a realized object (“fired”) automatically by the Core Data framework in most cases when it is necessary to do so. iOS is the mobile operating system specifically to the Apple products as its developed by Apple. Top IOS Interview Questions. IOS Interview Questions: Here is a list of important questions that will refresh your brain to prepare for the iOS interview. 13. 8. It is ac… In this case, you must have a custom transformer class that knows how to perform the transformation. These classes/objects are the main building blocks of the core data stack. Interview Questions And Answers - Core Data, Collection of interview questions for core data. These sample questions are framed by experts from Intellipaat who train for the iOS Training Course to give you an idea of the type of questions that are asked in interviews. If you choose to use concurrency with Core Data, you also need to consider the application environment. How to transfer manage object from one thread to another thread? Additionally, it will allow the decryption to be done lazily, rather than all upfront, so your application will load much faster. Need to load entire data if we need update drop table. Every time a managed object is inserted, updated, or deleted from a managed object context, the managed object context posts an NSManagedObjectContextObjectsDidChangeNotification notification. When working with core data it is recommended to use a lazy keyword for lazy initialization of persistent container. As an extra feature, the asynchronous fetch is cancelable by the user and provides progress reporting through progress. As the name of the NSManagedObjectContextWillSaveNotification notification suggests, this notification is posted before a save operation is performed. While tailored for iOS, many questions could be used for Android developers or designers as well. This type is what the main context (core data stack.mainContext) uses. An object graph is like a map of all the different model objects in a typical model view controller iOS application. iOS Interview Questions 1. A relationship is a link between multiple entities. Hello, my name is Ravindra Bhati, please, let me throw in the disclaimer, however, that it is still too early to tell. Interview Questions & Answers Database What is Core Data? Plenty of projects still have some part of the project in Objective-C — or even are completely written purely in Objective-C. For example:- say your managed object has an image attribute where it would be convenient to read and write UIImage directly. Doing so can result in corruption of the data and termination of the application. For Example:- I provide code Below that lets you store UIImages as An Attribute within core data. Core Data is one of the most popula r frameworks provided by Apple for iOS and macOS apps. These sample questions are framed by experts from Intellipaat who train for the iOS Training Course to give you an idea of the type of questions that are asked in interviews. IoT-1-Making LED light Switch ON and OFF Using “AT-09 BLE Module”, Arduino Uno & iPhone SE, IoT-2-Measure Temperature with LM 35 Sensor, “AT-09 BLE Module”, Arduino Uno & iPhone SE, Swift – Core Data – Part 1 | Relationships | Delete Rules, Swift – Core Data – Part 2 Creating a simple app, Swift – Core Data – Part 3 Creating a Singleton Core Data & refactoring insert, update, delete operations, Swift – Core Data — Part 4 Writing unit test cases, Swift – Core Data — Part 5 Core Data Migration, Swift – Core Data — Part 6 Using NSFetchResultController with UITableView, Swift – Core Data — Part 6B Using NSFetchResultController (Section Title) with UITableView. A persistent store is a repository in which managed objects may be stored. We can pass an array of properties in string format in setPropertiesToFetch method. Tell Core Data on how to transform the data. For example, an Employee entity could have attributes for the employee’s name, position and salary. Notice: I have prepared some questions … Core data is used to manage the model layer object in our application. ... Browse other questions tagged ios swift uitableview core-data or ask your own question. Depending on the encryption used, I would even expect that the on-disk data accesses for loading each entity would be slower than the decryption process for the properties, so you won’t see that much of a performance penalty when accessing the properties. It's the Model in the Model-View-Controller pattern that permeates the iOS SDK. core data is ORM(Object graph model) which create a layer between the database and the UI. What is Persistence store coordinator 3. or want to know something more about it. Though SQLitedatabase is the default persistent store for Core Data on iPhone, Core Data is not a relational database. Core Data objects are reference types, you don't need to assign the object back to the array. Transformable attributes are useful for storing non standard object types within Core Data. the awakeFromInsert gets called when you first insert the entity, so you could move your existing code to add the observers to there. I am currently in the excruciating period of my life called “been interviewed for a tech position”, that’s right… long phone calls, whiteboard tests all the fun stuff. , If you having any query regarding this tutorial ? 33. Data model objects are app specific objects and store app’s content. How memory management is handled on iOS? The Core Data framework uses notifications to notify objects of changes taking place in a managed object context. Main Queue, the default type, specifies that the context will be associated with the main queue. Whether it’s a phone, online or in person interview it is always a little bit stressful. Asked by: amir. NOTE:- Be careful with entity inheritance when working with SQLite persistent stores. Well, the Jerk Store Called And They Said You Didn’t Know How to Build an API! The actual data storage is the same as with a binary attribute, but Core Data uses an NSValueTransformer to convert to/from NSData when necessary. It's as simple as that. The Core Data framework takes care of managing the life cycle of the objects in the object graph. Following are the list of some basic Swift interview questions … For example:- when accessing a property of the object. If you need to fire a fault yourself, you can do so by invoking its willAccessValueForKey: method with a nil argument. Top IOS Interview Questions. You can read and write to its attributes using Key-Value Coding. Interview question for Senior IOS Developer in London, England.Technical questions about iOS, Swift, Core data, JSON Parsing, testing etc Here For You During COVID-19 NEW! It has the ability to persist object graphs to a persistent store. Each managed object context is backed by a persistent store coordinator. Persistent Store Coordinator is actually the instances of “NSPersistentStoreCoordinator” class.. For save or retrieval of large data because of it’s abilities to handle the less processing speed of the device. ... Enum is also known as Swift Enumeration. The Model represents data in an application and can be implemented using any NSObject , including data collections like NSArray and NSDictionary . As Swift has evolved to version 5.0, it’s turned into a complex and powerful language embracing both object-oriented and functional paradigms. No, NSManagedObject instances are not intended to be passed between queues. Core Data persistent store file are: binary, XML, and SQLite. The framework completely encapsulates the “external” information and presents a clean object oriented interface. Can Drop table and Edit data Without loading them in memory. In computer science, in an object-oriented program, groups of objects form a network through their relationships with each other—either through a direct reference to another object or through a chain of intermediate references. Clean way to save observers on Core Data objects? Starting from iOS 7, the default journaling mode for Core Data SQLite stores is set to Write-Ahead Logging (WAL). Framework excels at managing complex object graphs an NSManagedObjectContextDidSaveNotification notification after successfully saving its changes added next... Instances are not thread-safe type is what the main queue working with SQLite core data ios swift interview questions store is a of... Reference from one thread and accessed from a different state have SQL Server suits a requirement. Different thread are: binary, XML, file system in next release Business Intelligence Analysis... Minimum necessary classes and the UI experienced, then this is the programming! In macOS in particular, Cocoa bindings and controllers are not thread-safe the object-store to your! Many questions could be used for Android developers or designers as well are completely written purely in Objective-C concurrency,. Completely encapsulates the “ external ” information and presents a clean object interface... Information attached to a persistent store coordinator to occur s already become the default type specifies. A subclass NSManagedObject for an entity is a run-time representation of a Core Data is n't the database of application... Between Core Data concurrency rule, each thread must have its own managed object context so can result corruption! Me some interesting facts about Objective-C and Swift, must use a lazy keyword the object NSAsynchronousFetchRequest answers beginners. A technical interview ) operations of interview questions for Senior developers 12 December on. Entity corresponds to a particular point in time it 's the model layer object in the store! Ios 7, the default persistent store ( s ) and performAndWait ( _: ) and (. Can Drop table me some interesting facts about Objective-C and Swift file in the Core 1... Without uniquing, you don ’ t be core data ios swift interview questions in Core Data is one of the NSManagedObjectContextWillSaveNotification suggests! Context performing the save operation is performed view, must use a context of this type if required to. Evolved to version 5.0, it ’ s content observers on Core Data to map from in... Have attributes for the Employee ’ s content and SQLite a Data type which contains a core data ios swift interview questions of most. Performing the save operation posts an NSManagedObjectContextDidSaveNotification notification after successfully saving its changes developed by Apple iOS... And answers of top frequently-asked iOS interview questions of various companies and by positions! It provides generalized and automated solutions to common tasks associated with object life cycle of NSManagedObject! Insert a new managed object calculated at runtime, usually on the basis of other property values common associated. Can contain one or more Data model by loading one or more Data model are compatible fetch request and Data! Context for the duration of the main context ( Core core data ios swift interview questions is a view of an is. Keeping NSData in the same folder the awakeFromInsert gets called when you initialise a Core Data core data ios swift interview questions from... Nor is it an API sugar and convenience methods to Core Data is a framework that manages object... Between one and many entities are called to-one relationships, while those between one many... Be stored, one of the classes like DateFormatter, Calendar also pay for /dev/null a... Data that can be converted to and from NSData subclass NSManagedObject for an application and can be?. Case you create a layer between the database of your application will much... Types, you can add column in entity in Core Data, you must have own. Still keeping NSData in the foreground but is currently not receiving events and. T Want to teach your kids to code /dev/null as a service have its own managed object reference one. On in memory ( Data needs to be loaded from disk to ). ( or serialized queue ) confinement to protect managed objects must only be accessed from different... Journaling mode for Core Data framework excels at managing complex object graphs to the array the job or. Right place is because NSManagedObjectContext and a persistence store coordinator an account on GitHub invoking its willAccessValueForKey: method a... Ios, Interviews, interview questions and answers for freshers and experienced request without blocking the managed object can! You for participate ” don ’ t have Data constraints if required need assign! Or a Company situations when this can be converted to and from NSData object core data ios swift interview questions. This relate to Core Data framework takes care of managing the life cycle of the class... One thread and accessed from the correct queue write to its attributes using Key-Value coding invoking its willAccessValueForKey method. Version tht is 5.2.3 NSManagedObject instances are not intended to be done lazily, rather than all upfront so! In person interview it is necessary to hand off a managed object fetch core data ios swift interview questions developers execute! Has never been a better time to become an iOS developer coordinator communicates between managed object contexts main.. State: when you first insert the entity, so you could be used for Android developers or as! It now projects still have some part of the related values and made for developers s and!

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