What is nonnull in objective C?

Question

Can someone elaborate why is nonnull introduced in iOS 9 ?

For example, the NSArray method + (instancetype)array; is now + (

Answer 1

They have made sure that wherever the type is not-nullable it is now a nonnull type.

Like earlier NSMutableArray addObject method was

- (void)addObject:(ObjectType)anObject  

and now it has been changed to

- (void)addObject:(ObjectType nonnull)anObject

So it means you cannot pass a null object (nil) to this method. Same way, in your case

+ (instancetype nonnull) array

method will never return nil.

Reference: https://developer.apple.com/swift/blog/?id=25