Swift and Objective-C. It's as simple as that. I will come back with more questions and answers. 17. If you are looking for iOS Development interview questions for the beginner or experienced, then this is the right place. “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”. The Core Data framework excels at managing complex object graphs. I hope you will like this. The different iOS application states are: Not running state: when the app has not been launched or was running but was terminated by the system. ♥♥️♥️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. iOS Interview Questions For Senior Developers 12 December 2015 on iOS, Interviews. We have taken full care to give the top answers to all the questions. ... 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. This factor in the design of the SQLite persistent store can create a performance issue. 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. 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. How we can do multithreading with core data? An asynchronous fetch allows developers to execute a fetch request without blocking the Managed Object Context for the duration of the fetch. ALLInterview.com. Core data API is provided by apple for persisting data in SQL, XML, file system. ... Now for the important part: go to the the iOS simulator, then choose the Hardware menu and Erase All Content And Settings. Data model objects are app specific objects and store app’s content. These are the basic questions generally asked in Core data 1. 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. A controller that you use to manage the results of a Core Data fetch request and display data to the user in UITableView. 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. Yes, but can’t create relationships between objects in different stores. 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). 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. 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. 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. An attribute is a piece of information attached to a particular entity. For example:- say your managed object has an image attribute where it would be convenient to read and write UIImage directly. A. 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. Swift Interview Questions: IOS swift is the latest programming language. It also suits a business requirement where you have a model with it’s attributes. Wrapper libraries provide some much needed syntactic sugar and convenience methods to Core Data’s verbose and complicated APIs. We can use the NSFetchRequest class’s property “setPropertiesToFetch”. 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 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. How you can add column in entity in core data that can be also added in next release? An Entity can be abstract, in which case it is never directly attached to a managed object. Data is organized into relational entity-attribute model. Any UI operation, such as creating the fetched results controller for the table view, must use a context of this type. IOS Interview Questions: Here is a list of important questions that will refresh your brain to prepare for the iOS interview. 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 This type is what the main context (core data stack.mainContext) uses. Core Data isn't the database of your application nor is it an API for persisting data to a database. In this case, Core Data will attempt to call encodeWithCoder: on your object to convert it to NSData. Private Queue specifies the context that will be associated with a private dispatch queue instead of the main queue. They are calculated at runtime, usually on the basis of other property Values. What is ManagedObject 2. Persistence store coordinator communicates between managed object context and store. These classes/objects are the main building blocks of the core data stack. 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. One wrong answer during your first interviews can determine if you get the job, or just a “thank you for participate”. All entities that inherit from another entity exist within the same table in SQLite. 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. 39. what is the Difference between core data and SQLite? 14. For Example:- I provide code Below that lets you store UIImages as An Attribute within core data. 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 … It's the Model in the Model-View-Controller pattern that permeates the iOS SDK. 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. Our experts will answer them for you. The Overflow Blog Want to teach your kids to code? 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. 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. Except, UIImage can’t be saved in Core Data. Swift and Objective-C iOS isn’t just about Swift. It defines the core components of an iOS application, from labels and buttons to table views and navigation controllers. What is lazy initialization, how does this relate to core data, situations when this can be handy? 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. Object-oriented applications contain complex webs of interrelated objects. Objects are linked to each other by one object either owning or containing anoth… Plenty of projects still have some part of the project in Objective-C — or even are completely written purely in Objective-C. You can encrypt individual properties in your Core Data model entities by making them transformable properties, then creating an NSValueTransformer subclass which will encrypt and decrypt the data for that property. Following are the list of some basic Swift interview questions … 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. 32. Without uniquing, you might end up with a context maintaining more than one object to represent a given record. Can we do Multithreading with core data? An app stays in this state briefly as it transitions to a different state. A Managed object model allows core data to map from records in a persistent store to managed objects that you use in your Application. What is NSPersistentStoreCoordinator? Doing so can result in corruption of the data and termination of the application. While tailored for iOS, many questions could be used for Android developers or designers as well. What is Cocoa and Cocoa Touch? 12. Here is the list of most frequently asked iOS Interview Questions and Answers in technical interviews. We have created a list of top frequently-asked iOS interview questions that will help you ace your iOS job interview. It provides generalized and automated solutions to common tasks associated with object life cycle and object graph management, including persistence. NOTE:- Be careful with entity inheritance when working with SQLite persistent stores. Core Data can then manage object instances at runtime to provide the following features. How to transfer manage object from one thread to another thread? For example:- when accessing a property of the object. iOS Domain is pretty enormous and deep. For the most part, AppKit and UIKit are not thread-safe. 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 is ac… How to read only a few attributes of an entity? or want to know something more about it. You can read and write to its attributes using Key-Value Coding. Follow guide for iOS Developer/Engineer interview. core data is ORM(Object graph model) which create a layer between the database and the UI. The model is a collection of entity description objects(instance of NSEntityDescription). 16. Here are the top 19 sample iOS interview questions and their answers. 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 … Concurrency is the ability to work with the data on more than one queue at the same time. Core data is used to manage the model layer object in our application. 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. We need NSManagedObject, NSManagedObjectContext and a Persistence store container. 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. 5. The Core Data framework uses notifications to notify objects of changes taking place in a managed object context. Jobs In a database, an attribute corresponds to a particular field in a table. To fetch the data asynchronously in a background queue, Core Data provides the object NSAsynchronousFetchRequest. What types of stores does core data support? However, if you have already given an iOS interview, or have more questions, we encourage you to add them in the comments tab below. These groups of objects are referred to as object graphs. Persistence. Core Data consist of following stack objects: 5. Apple iOS Swift technical job interview questions of various companies and by job positions. Interview questions for testing anti virus software for apple products. Core Data is a framework that … What is Latest Version of iOS & Swift ? Managed object context can contain one or more managed object model instances. With the WAL mode, Core Data keeps the main .sqlite file untouched and appends transactions to a .sqlite-wal file in the same folder. What is the minimum necessary classes and the relationship between them? Is Core Data == SQLite or some wrapper? Apps can also use document objects to manage some or all of their data model objects. Transient properties are properties on an NSManagedObject that are not persisted t the object-store. What is Faulting mechanism in Core Data? 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. How can I encrypt Core-Data contents on an iPhone? Ans : When you initialise a Core Data stack, one of the steps involved is adding a store to the persistent store coordinator. So, You Want to Scan a Billion Files in a Day. The Core Data framework takes care of managing the life cycle of the objects in the object graph. 8. Main Queue, the default type, specifies that the context will be associated with the main queue. In Core Data, relationships between two entities are called to-one relationships, while those between one and many entities are called to-many relationships. 4. NSManagedObjectContext has perform(_:) and performAndWait(_:) to direct work to the correct queue. According to the Core Data concurrency rule, each thread must have its own managed object context. https://harsivo.com/Here i have covered 15 iOS interview questions and answers. Top Swift (iOS) Interview Questions and Answers with Examples: Swift is a powerful and interactive programming language created for iOS, macOS, tvOS and watchOS, and Linux development by Apple Inc. What is an abstract entity in core data? 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.
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