Explanation: This question tests understanding of how views are positioned and sized within their parent view.

Answer:

• frame: Represents the view’s location and size in its superview’s coordinate system. It is a rectangle defining the view’s position relative to its superview.
• bounds: Represents the view’s location and size within its own coordinate system. It defines the view’s internal coordinate space, including its width and height.

Example: If a view is positioned 20 points from the left and 30 points from the top of its superview, the frame might be {20, 30, width, height}. The bounds will usually be {0, 0, width, height}, unless you apply transformations like scaling or rotation.

Explanation: This question assesses understanding of memory management in iOS development.

Answer:

• ARC: Automatic Reference Counting is a memory management feature of the Objective-C and Swift programming languages. It automatically manages the memory of objects by keeping track of their references.
• How It Works: ARC inserts retain and release calls at compile time to ensure that objects are kept in memory as long as they are needed and released when they are no longer in use. This helps prevent memory leaks and reduces the need for manual memory management.

Example: When you create an object and assign it to a variable, ARC keeps track of the reference count. If the count drops to zero (i.e., no more references to the object), ARC automatically deallocates the object.

Explanation: This question evaluates knowledge of design patterns used in iOS development.

Answer:

• Delegate Pattern: A design pattern where one object (the delegate) acts on behalf of or in coordination with another object (the delegator).
• Usage: Used to communicate between objects in a decoupled manner. For example, UITableView uses a delegate to handle row selection, cell configuration, and other interactions.
• Implementation: Define a protocol with methods for the delegate to implement, and set the delegate property of the delegator object to the object that conforms to the protocol.

Explanation: This question tests knowledge of concurrency and asynchronous programming in iOS.

Answer:

• Grand Central Dispatch (GCD): Provides a low-level API for managing concurrent tasks. It uses dispatch queues to execute code asynchronously or synchronously. GCD is lightweight and suitable for most tasks.
• NSOperationQueue: A higher-level API for managing concurrent operations. It provides more control and flexibility, such as operation dependencies and cancellation. NSOperationQueue can handle complex scenarios involving multiple operations with specific dependencies.

Explanation: This question assesses understanding of architectural patterns used in iOS app development.

Answer:

• MVC Pattern: A design pattern that separates an application into three interconnected components:
  • Model: Manages the data and business logic of the application.
  • View: Handles the presentation and user interface.
  • Controller: Acts as an intermediary between the Model and View, processing user input and updating the Model and View accordingly.
• Application in iOS: In an iOS app, the UIViewController often acts as the Controller, managing interactions between the Model (data) and View (UI elements).