iOS Interview Prep 5 — Singletons

The purpose of this interview preparation series is to assist you in quickly refining your interview skills and thoroughly preparing for the typical questions asked during an iOS interview. If you find it useful, please leave a comment or tap the like button.

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Interview Questions

• What is Singleton and how is it used in iOS development?
• Can you explain the Singleton design pattern and its advantages?
• What are the possible ways to prevent multiple instances of Singleton in a multithreaded environment?
• Can you give an example of when you would use Singleton in your iOS app?
• How do you test Singleton in iOS?

Overview

The singleton pattern is a design pattern that ensures that a class has only one instance, and provides a global point of access to that instance. This can be useful when a class needs to be shared across multiple parts of an app, but it is not practical or desirable to create multiple instances of the class. In iOS, the singleton pattern is a commonly used design pattern.

How to implement a Singleton?

One frequent concern with singletons is that often they’re not thread-safe. They are often used from multiple…