Top iOS Interview Questions You Must Prepare In 2020

With the number of iOS users rising regularly across the world, the future looks favorable for iOS app developers. Apple and iOS devices remain to have a faithful customer base, helped in part by innovative modern devices such as Apple TV and Apple Watch. With that said, an iOS app development certification is apparently the most straightforward way to hone and prove your experiences in the same. There has never been a more suitable time to become an iOS developer. If you are anticipating to break into a profession in iOS app development, then look no further! We have devised a list of topmost frequently-asked iOS interview questions that will support you pass your iOS job interview.

iOS Interview Questions

Let us have a look at the major iOS interview questions.

Which JSON framework is supported by iOS?

iOS supports SBJson framework as it provides extensible APIs and extra control, making JSON handling more comfortable.

What is the contrast between atomic and nonatomic properties? Which is the default for synthesized properties?

Properties defined as atomic constantly return a fully initialized object. This also appears to be the default state for synthesized properties. But, if you have a property for which you know that recovering an uninitialized value is not a risk then setting it to nonatomic can give you more reliable performance than atomic.

Differentiate ‘app ID’ from ‘bundle ID’. Explain why they are used.

An App ID is a two-part string. It used to recognize one or more apps from a single development team. The string comprises of a Team ID and a bundle ID search string. A period (.) will be dividing the two parts. 

The bundle ID represents each App and is stipulated in Xcode. A single Xcode project can have varied targets and therefore output multiple apps. 

Which are the forms of performing concurrency in iOS?

The three approaches to accomplish concurrency in iOS are Threads, Dispatch queues, and Operation queues.

Describe the different types of iOS Application States.

The various iOS application states are:

Not running state: This is the state when the app has not been launched. Also in case it was running but was terminated by the system.

Inactive state: Here the app is running in the foreground but is right now not receiving events. 

Active state: This is the normal state when the app is running in the foreground and is receiving events. 

Background state: Here the app is in the background and executing code. Most apps enter this state before they are being suspended. 

Suspended state: A suspended app stays in memory. Still, it does not execute or run any code. When a situation of low-memory arises, the system may kill or remove suspended apps without prior notice to make additional space for the foreground app.

Name the framework that is utilized to construct the application’s user interface for iOS?

The UIKit framework is applied to produce the application’s user interface for iOS. It presents event handling, windows, views, drawing model, and controls specially designed for a touch screen interface.

Name the application thread from where UIKit classes are be used? 

Only for the main thread.

Which API would you use to write test scripts to handle the application’s UI elements?

UI Automation API is applied to automate test procedures.

What is Swift and what is Objective-C?

Objective-C is the principal programming language you use to write software for OS X and iOS. Moreover, it’s a superset of the C programming language. And it presents object-oriented abilities and an active runtime. Objective-C receives the syntax, primitive types, and flow control statements of C and supplements syntax for defining classes and methods. 

Swift is a modern programming language for iOS, OS X, watchOS, and tvOS apps that builds on the most excellent of C and Objective-C, without the limitations of C compatibility. Swift embraces safe programming models and adds modern highlights to make programming more accessible, more flexible, and more fun. Swift feels close to Objective-C developers and is friendly to new programmers.

What is SpriteKit and what is SceneKit?

SpriteKit is a framework used for animated 2D objects. SceneKit is a framework inherited from OS X to support 3D graphics rendering.

What are iBeacons?

iBeacon.com defines iBeacon as Apple’s technology example which provides Mobile Apps to hear for signals from beacons in the physical world and respond correspondingly. 

Differentiate between the ‘assign’ and ‘retain’ keyword.

Retain specifies that retain should be entreated on the object upon assignment. It regards ownership of an object. Whereas as Assign specifies that the setter practices simple assignment. It is used on the property of scalar type like float, int.


However, if you have previously given an iOS interview, or have more questions, we prompt you to add them in the comments tab below. Our experts will clarify them for you. For finding a career for you in iOS development, we provide excellent iOS training in Kochi at iROHUB Infotech. Join us soon and pursue your dream career.


Post Comments (0)

Leave a reply