iOS Developer Interview Preparation Guide

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Swift is a programming language for development of applications for OS X, iOS, watchOS, and tvOS. These applications are developed using C and Objective-C. It does not have the constraints of C Programming. It has features for easier development and provides more flexibility.

.xib is a file extension that is associated with Interface Builder files. It is a graphics software that is used to test, develop and design the User Interfaces of different software products. Such extension files also contains development time format files that includes interface files created with the interface builder softwares.

Fast enumeration is a iOS Programming Language feature that enables you to enumerate over the contents of a collection. It will also make your code execute your code faster due to internal implementation which gets reduced message sending overheads and increased pipelining potential.

Category enables to add methods only. It does not allow the inclusion of Data Members unlike Inheritance where both the Data and Methods can be added. Category includes Complete Application in its Scope whereas Inheritance’s scope is only within that particular File.

The entire set of data of an object can be made a user-defined data type using a class. Objects are basically variables of Class type. Once a Class has been defined, it is possible to create multiple Objects of its type. A Class is a collection of Objects of similar type.

IPA represents iOS App Store Package. It has an .ipa extension which represents iPhone application archive file that stores an iPhone application. Every file is compressed with a Binary for the ARM architecture and can only be installed on an iPhone, ipad or an iPod Touch. It is mostly encrypted with Apple’s FairPlay DRM Technology.

Every time -autorelease is sent to an object, it is added to the inner-most autorelease pool. When the pool is drained, it simply sends -release to all the objects in the pool.
Autorelease pools are simply a convenience that allows you to defer sending -release until "later". That "later" can happen in several places, but the most common in Cocoa GUI apps is at the end of the current run loop cycle.

Cocoa is an Application Development Environment for Mac OS X Operating System and iOS. It includes Compilations of a Runtime System, Object-Oriented Software Libraries and an Integrated Development Environment.

The Web Services are the Application Components which enables communication using Open Protocols. These Web Services are Self – Describing and Self – Contained. Web Services can be found out by using UDDI. The base for development of Web Services functionality is Extensible Markup Language (XML).

There is a huge difference between these two. SQLLite is a database itself like we have MS SQL Server. But CoreData is an ORM (Object Relational Model) which creates a layer between the database and the UI. It speeds-up the process of interaction as we dont have to write queries, just work with the ORM and let ORM handles the backend. For save or retrieval of large data, I recommend to use Core Data because of its abilities to handle the less processing speed of IPhone.

Objects are essentially the variables that are of Class types. Objects are basic Run-Time entities in an Object oriented system. They may represent a place, a bank account or a person.

AutoRelease: When you send an Object AutoRelease message, it gets added to the Local AutoRelease Pool. When the AutoRelease Pool gets destroyed, the Object will receive a Release
message. The Garbage Collection functionality will destroy the Object if it has the RetainCount as Zero.

An application is notified whenever the Operating System transfers the application between Background and Foreground. It helps in extended battery life by determining the exact functionalities in the background and thereby also helps in a better User Experience with the Foreground Application.

It is basically a conceptual structure or a scheme with an intension to support the expansion of the structure into something useful. A Framework is a layered structure indicating what kind of programs can or should be built and how they would interact. Frameworks includes actual programs that mentions programming interfaces and programming tools for working with the frameworks.

ApplicationDidFinishLaunchingWithOption -ApplicationWillResignActive- ApplicationDidBecomeActive-ApplicationWillTerminate

The @synchronized()directive locks a section of code for use by a single thread. Other threads are blocked until the thread exits the protected code.

*Weak - weak reference you signify that you don't want to have control over the object's lifetime. The object you are referencing weakly only lives on because at least one other object holds a strong reference to it. Once that is no longer the case, the object gets destroyed and your weak property will automatically get set to nil.

Mutable Types means you can modify the Contents later when you feel the need. However, when an Object is marked as Immutable, it implies that the data cannot be modified later after it has been initialized. Therefore, the stored values are Constant here.

Example:
NSString, NSArray values cannot be altered after initialization.

The Bundle ID uniquely defines every iOS Application. It is specified in Xcode. It is a Search String which is supplied by the Application Developer to match either the Bundle ID of a Single Application or a Set of Bundle IDs for a Group of Applications.

Xcode is a combination of Software Development Tools developed by Apple for developing applications. It is an Integrated Development Environment (IDE). It is primarily used for development of iOS and OS X applications.

The recent iOS Development platforms are as follows:
iOS 9.2 beta 2 Build version: 13C5060d
IOS 9.1 Build Version: 13B143

By using -
1. Static analyzer.
2. Instrument

*Objective-C is a reflective, object-oriented programming language which adds Smalltalk-style messaging to the C programming language. strictly superset of c.

By using NSJSONSerialization.
For example : NSArray *jsonArray = [NSJSONSerialization JSONObjectWithData: data options: NSJSONReadingMutableContainers error: &e];

A protocol declares methods that can be implemented by any class. Protocols are not classes themselves. They simply define an interface that other objects are responsible for implementing. Protocols have many advantages. The idea is to provide a way for classes to share the same method and property declarations without inheriting them from a common ancestor