What is Cocoa?

What are the characteristics of the category in Objective C?

What are layer objects in iOS?

What is UIWindow object in iOS?

what are the build phases in Xcode?

What is difference between Cocoa and Cocoa Touch ?

What is the First Responder and Responder Chain in iOS

What are the ways to achieving concurrency in iOS?

What is the difference between delegate and notification?

What is KVO in iOS ?

What is KVC in iOS?

What is a protocol in iOS?