Objective-C nullability for output parameters

Question

I\'m adding nullability specifiers to a class, and I have some pointer-to-pointer output parameters, like (NSString**), because the method returns multiple obje

Answer 1

You have two pointers so you need two nullability specifiers.

- (void)someMethod:(NSString * _Nullable * _Nonnull)out

This means you must pass in a non-null pointer but you may get back a null result.

This will fail:

[someObject someMethod:nil];

This will work:

NSString *result = nil;
[someObject someMethod:&result];