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    iOS Interview Questions

    Frequently Asked Interview Questions And Answers For iOS Freshers

    How Could You Setup Live Rendering in iOS?

    We can use IB Designable that helps the interface builder to update on a particular view. We have to define Init frame in UIView class.

    What is The Difference Between Synchronous & Asynchronous Task In iOS?

    We find the synchronous task as we have to wait until the task is completed.

    Explain Compilation Conditions in iPhone?

    We can use Compilation conditions structure ifDEBUG..endif to include or disable a given block of code to separate targets.

    What is Made Up of NSError Object In iOS?

    NSError object has 3 main types: a domain, an error code, and a user info dictionary. The domain is like a string that identifies what categories of the error are coming in.

    What is Enum or Enumerations In iOS?

    According to Apple’s Swift documentation:
    We can keep track of how our app is being used by storing it in bytes as data at the moment. every enumeration denotes the different individual states of the application so we can use it to make a model of state and its internal processes.
    The Group of related values in the same umbrella is called enum. The case-less enum doesn’t allow the developer to create an instance of it.

    What is The Bounding Box in iOS?

    The Bounding Box is the smallest term or value within which a set of value is given in terms of geometry.

    Why Don’t We Use Strong For Enum Property in Objective-C?

    We don’t use strong for enum property in Objective-C because enums aren’t objects so we can ‘t specify them as strong or weak.

    What Is @Synthesize in Objective-C?

    Synthesize is used to create the getter and setter method for your property.

    What is @Dynamic in Objective-C?

    The @dynamic is used to tell the compiler that the getter and setter are applied anywhere else.

    Why Do We Use Synchronized in iOS?

    Synchronized is used to execute one code of block by only one thread at a time.

    What is The Difference Strong, Weaks, Read Only And Copy in iOS?

    These three properties are assigned to know how memory for that property will be managed.
    Property strong defined as that the reference count will be increased but the reference to it will remain the same of all the lifetime of the object.
    We can use Weak reference to point the object, it doesn’t increase its reference count. We can use weak reference while creating a parent-child relationship, where the parent has a strong reference to the child but the child has a weak reference to the parent.
    • Every time used on var
    • Every time used on an optional type
    • It Automatically changes itself to nil
    Read-only, We can use this property initially but it can’t be changed.
    Copy It means that we have copied the value of the object while the creation of the object. We can prevent its value from changing.

    What is Dynamic Dispatch?

    Dynamic dispatch means that it is the process of selection of the implementation of a polymorphic operation like a method or a function to call at runtime. the Swift doesn’t default of dynamic dispatch.

    What’s Code Coverage?

    We can use Code Coverage to measure the value of our unit tests.

    What’s Completion Handler?

    The best use of the Completion handler is when we are going to make an API call and we have to show the changed value in the UI, the data from the API call. There is the Completion of handlers dataTaskWithRequest in Apple’s API.

    It takes the code with the three arguments:(NSData?, NSURLResponse?, NSError?) that returns nothing: Void. It’s a closure.

    We have to mark Completion handlers as @escaping since they are executed some point after the enclosing function has been executed.

    How To Prioritize Usability in Design in iOS?

    We have partitioned the design process to prioritize usability in 4 steps.
    1) We have to design the UX like we are the user.
    2) We have to remember that the users are people, not demographics.
    3) We have to check each and situations which can be useful while promoting the application.
    4) We have to keep working on the utility of the app even after launch.

    What’s the Difference Between The Frame And The Bounds In iOS?

    The UIView ‘s bound is rectangle, expressed as (x,y)and size(width,height) is relative to its own coordinate system(0,0).

    The UIView’sframe is the rectangle and expressed as a location(x,y) and size(width, height) relative to superview is contained within.

    What is Responder Chain In iOS?

    The Hierarchy of the objects have the opportunity to respond to the events received is called the ResponderChain.

    What is Regular Expressions In iOS?

    Regular Expressions are the special strings that help developers to search through to a string.

    What is Operator Overloading in iOS?

    Operator Overloading means how existing operators will behave with types that both already exist.

    What is TVMLKit in iOS?

    TVMLKit works as glue to stick between TVML, JavaScript, and our native tvOs application.

    What is Platform Limitations of TVOS?

    First, There is no web browser support need to run any tv, or there is no any other web-based rendering engine we can program against. It means our app can’t have links out to a web browser for anything, that include any link, OAuth or a social media connection.
    SecondtvOS apps cant have access to the local storage, I that provided 32 GB or 64 GB of hard-drive at product launch.
    tv app bundle cannot exceed 4 GB.

    What is Functions In iOS?

    When We Are using the same task again and again in the code we should create a function and we can use it by the function name.

    What is ABI in iOS?

    When we are using external libraries in the programs that we update it later then we don’t have to re-compile the application(from the end-point of end user). If the updated library uses the same ABI then your program will not need to change.

    Why is Design Pattern Very Important in iOS?

    Design patterns are the pre-written code that helps the developer in common problems in software design. It is in the form of templets designed to help you write code that Is easy and understandable.
    • Creational: Singleton.
    • Structural: Decorator, Adapter, Facade.
    • Behavioral: Observer, and, Memento

    What is Singleton Pattern in iOS?

    The Singleton Class is used when we want to create the global access point to the instance and it is only one instance of the class then it is called singleton class.

    What is Facade Design Pattern in iOS?

    We can use the Façade design pattern to provide a single interface to the complex system.
    We can hide all the system classes by exposing only one simplified API by hiding a set of classes and their API’s.

    What is Decorator Design Pattern in iOS?

    The decorator pattern helps the developers by adding behavior and responsibility dynamically to an object without modifying the code.

    In Objective-C, there are two very common implementations of this pattern: Category and Delegation. In Swift, there are also two very common implementations of this pattern: Extensions and Delegation.

    What is Adapter Pattern in iOS?

    An Adapter is used to join two classes with incompatible interfaces to work together. We can wrap it around the object and exposes the standard interface to interact with that project.

    What is Observer Pattern in iOS?

    Observer pattern’s work is to show the changes in the other objects changes to one object.
    Cocoa implements the observer pattern in two ways: Notifications and Key-Value Observing (KVO).

    What is Memento Pattern in iOS?

    We can store our private data somewhere and we can restore it without disturbing encapsulation. Thus, private data remains private. There is Apples’s specialized implementation of Momento pattern as part of State Restoration.

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