30+ iOS Interview Questions And Answers

Synchronous tasks wait until the task is finished before moving on to the next line of code, while asynchronous tasks can complete in the background and notify you when they're done, allowing the program to continue running other code.

An escaping closure is a closure that is passed as an argument to a function but is called after the function returns. It is used for operations that work with asynchronous callbacks, like network requests.

Generics are a way of writing flexible and reusable code. They allow you to define functions and types with placeholders that can be filled in with any type, reducing duplication and increasing code clarity.

Dependency injection is a design pattern that allows a class or structure to be decoupled from its dependencies. It involves providing the dependencies from the outside instead of constructing them within the object.

Memory is managed automatically through Automatic Reference Counting (ARC). Developers must be mindful of strong reference cycles that can keep objects alive when they should be deallocated. These can be prevented with 'weak' and 'unowned' references.

The 'guard' keyword is used to provide early exit from a function. It's often used for checking validity of conditions and to make code safer and cleaner by handling possible error cases at the beginning of functions.

Autolayout is a system that allows developers to create a dynamic and flexible user interface that adjusts to different device sizes and orientations by defining constraints that govern the layout.

A completion handler is a type of closure that's passed as an argument into a function and is intended to be called once that function has completed its execution, usually to signal that a long-running task is finished.

Error handling in Swift is done using a combination of do-catch, 'try', and 'throw'. Errors can be thrown by functions and caught by 'catch' blocks where you can handle or rethrow them.

The defer statement is used to schedule execution of code to just before the current scope exits. It ensures that cleanup or other necessary operations are performed even if an error occurs in the middle of the function.

Protocol-oriented programming is a paradigm in Swift that encourages the design of software around protocols and their implementations rather than relying on inheritance. It enables more flexible and reusable code.

Reactive programming is a declarative programming paradigm concerned with data streams and the propagation of change. It enables developers to build more dynamic applications with data that can automatically update UI when it changes.

Continuous integration is a software development practice where developers frequently integrate code into a shared repository. It helps detect issues early and improves the quality of the software.

Multi-threading in iOS can be handled through APIs like Grand Central Dispatch and NSOperationQueue. These provide a way to perform tasks concurrently to keep the UI responsive while executing background tasks.

The Singleton pattern guarantees that a class has only one instance and provides a global point of access to it. It's useful for managing resources that should be shared across an application, like a network manager.