ObjC method type encoding string for a method with a Block parameter

Question

I'm reading Apple's article about Objective-C runtime type encoding strings but I do not understand how to encode a method with a Block parameter.

For example, I have this :

- (void)userNotificationCenter:(UNUserNotificationCenter *)center didReceiveNotificationResponse:(UNNotificationResponse *)response withCompletionHandler:(void(^)())completionHandler

I don't understand what to use for (void(^)())completionHandler

Maybe it will help http://stackoverflow.com/questions/2172758/encoding-an-objective-c-block — schmidt9, Apr 29 '17 at 17:44
What are you trying to do, exactly? Depending on context, the answer will vary. — bbum, May 14 '17 at 18:34

score 1 · Answer 1 · answered Apr 29 '17 at 17:46

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All object types are @. Therefore I would expect this, because blocks are objects in Objective-C.

However, you can ask the runtime itself with method_getTypeEncoding().

answered Apr 29 '17 at 17:46

Amin Negm-Awad

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Sulthan · Answer 2 · 2017-04-30T14:46:16.507

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When in doubt, use the @encode directive:

typedef void(^CompletionHandler)(void);

char *encoded = @encode(CompletionHandler);
NSLog(@"Encoded: %s", encoded);

prints @?.

To quote your documentation link:

@ An object (whether statically typed or typed id)
? An unknown type (among other things, this code is used for function pointers)

edited Apr 30 '17 at 14:46

answered Apr 30 '17 at 14:39

Sulthan

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`@encode()` emits different encodings than the compiler does for methods. This may not answer OP's question. – bbum May 14 '17 at 18:34
@bbum Really? I also tried `method_getTypeEncoding()` and I got the same result. – Sulthan May 14 '17 at 18:57
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`@encode` doesn't include the (now bogus) stack offsets. – bbum May 14 '17 at 20:24

ObjC method type encoding string for a method with a Block parameter

2 Answers2