iOS Interview Questions (Part-2) Basics

2 min readFeb 10, 2021

Welcome to part -2 of the Interview question series, these blogs will definitely help you in your job search.

Questions based on Application Life Cycle

What is the first line of code gets executed when you click on the app icon for the very first time (hint: It's in the App delegate file but definitely not sidfinishLaunchOption)
Ever experienced an application getting crashed in AppDelegate (Why does it crash there and when does it crash there)
What State of an iOS application is when you are receiving a phone call.
Explain all of the states of An application life Cycle with example(e.g. What would be the state of an application when a phone call comes.)
If we have minimized App in from the background then What are the delegates function will be called

Can we create a duplicate AppDelegate Class? (If Yes then how we will inform which one is our main AppDelegate Class).
What is the different delegate's function of AppDelegates Class?
What would happen if we rename the AppDelegate Class?
Is AppDelegate Is Singleton class or not(It might leads you to Questions about the Singletons and more)
What will happen if we Delete the AppDelete Class.

What are Singleton classes?
How to create Singleton classes
Are singletons are Thread Safe Or not (If NO then can we make it thread-safe . they could ask you to write the code)
What is Singleton design patterns?
What is the scope of singleton class(When does do they get de-initialized from the classes