How to use nonnull and nullable Objective-C keywords in block-based API method

Question

Consider the following method

- (void)methodWithArg:(NSString *)arg1 andArg:(NSString *)arg2 completionHandler:(void (^)(NSArray *results, NSError *error))co         


        

Answer 1

To define completions in a header file I did this

typedef void (^PublicEventsHandler) (BOOL success, NSArray * _Nullable publicEvents);

Of course, I agree with the accepted answer.