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iOS Interview Questions and Answers

Related differences

Android vs iOS

Ques 1. What is iOS?

iOS stands for "iPhone Operating System".

It is the operating system for Apple devices, and it is considered the second most popular mobile operating system globally after Android.

This operating system powers many of Apple's products including the iPhone, iPad, and iPod. iOS is widely praised for its intuitive and user-friendly interface.

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Ques 2. What are the features of the iOS Platform?

  • The iPhone offers multitasking capabilities. On an iOS device, you can easily switch between apps using the multitasking feature or a multi-finger gesture.
  • iOS helps you easily integrate social network interactions with your app by displaying an activity stream and sharing content.
  • Apple's iCloud service allows users to store data on the Internet. It offers a high level of encryption and a backup option to ensure the user does not lose data.
  • Apple's in-app purchases are available on all platforms, offering users additional services and materials including digital items (iOS, iPad, macOS), subscriptions, and premium content.
  • You can see all of your app alerts in the Notification Center in iOS. However, the notification settings can be modified.
  • iOS is a closed system. The source code of Apple's apps isn't available for developers, and iPhone and iPad owners can't modify the code on their devices. This makes iOS-powered devices harder to hack.

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Ques 3. Explain the Architecture of iOS.

iOS operates in a Layered structure.

iOS Architecture is comprised of four layers, each of which offers a programming framework for creating applications that operate on top of the hardware. Communication will be enhanced by the layers between the Application Layer and the Hardware Layer. A lower-level layer provides the services that all applications require, while an upper-level layer (or high-level layer) provides graphics and interface-related services.

  • Core OS ( or Application) Layer: Core OS Layer sits directly on top of the device hardware and is the bottom layer of the iPhone OS stack. In addition to basic operating system services, such as memory management, handling of file systems, and threads, this layer provides low-level networking, access to external accessories, etc.
  • Service Layer: Its purpose is to design the services that upper layers or users demand. Among its other essential features are block objects, Grand Central Dispatch, in-app purchases, and iCloud storage. The service layer has been strengthened by the addition of ARC Automatic Reference Counting.
  • Media Layer: It handles media like video, audio, graphics, etc. The media layer will allow us to use all graphics, video, and audio technology of the system.
  • Cocoa Touch Layer: It is also known as the application layer. This is the place where frameworks are created when applications are built. In addition, it functions as the interface for iOS users to work with the operating system. This includes touch and motion capabilities.

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Ques 4. What do you mean by property in iOS?

Properties are basically values that are associated with a class, struct, or enum.  They can be thought of as "sub-variables," i.e., parts of another object.


struct Building  {    

    var name: String = ""


var apartment = Building() = "Prestige"

In the above code, we created a structure called Building. One of its properties is called name, a String whose initial value is empty. 

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Ques 5. Define the classification of Properties in iOS.

Stored Properties: This type of property can be used to store constant or variable values as instances and is usually provided by classes and structures.

class Programmer {    

    var progName: String    

    let progLanguage: String    

    var totalExperience = 0    

    var secondLanguage: String?



Computed properties: These properties can be used to calculate values instead of storing them and are usually provided by classes, enumerations, and structures.

struct Angle {    

    var degrees: Double = 0    

    var rads: Double {        

        get {            

             return degrees * .pi / 180        


        set(newRads) {            

              degrees = newRads * 180 / .pi        




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