CODEWITHSUNDEEP
iosobjective-c
bluekurk
bluekurk

Reputation: 21

respondsToSelector can not recognise the implemented selector

In a simple subclass of UIViewController I just implemented a selector as a callback to refresh UI

-(void)afterfollowAction:(id)object{
  //blabla
}

but finally I found respondsToSelector can not recognise it. Test code:

SEL callback = @selector(afterFollowAction:);
BOOL test1 = [self respondsToSelector:callback]; //NO
BOOL test2 = [self respondsToSelector:@selector(afterFollowAction:)]; //NO
BOOL test3 = [[self class] instanceMethodForSelector: @selector(afterFollowAction:)];  //YES
BOOL test4 = [self respondsToSelector:@selector(viewWillDisappear:)]; //YES
[self performSelector:callback withObject:nil]; //crash

test2 shows not the local variable callback's issue,

test4 shows it knows it is a UIViewController and self is not nil

test3 shows actually it knows the selector is implemented

but if you invoke it with "performSelector" it throw exception "unrecognized selector"

I searched the web and I did not make error with ":" or nil thing;

I put the declaration of the selector to the header file, but makes no use.

I restarted the Mac and iPhone but it is the same result.

This is a simple class in which I do not re-implement respondsToSelector: selector.

So, Did I make wrong use of respondsToSelector? I just want to make the callback outside this class.

Environment: Mac OS X 10.11.3, Xcode 7.2.1, iOS 9.2.1

Update: find(cmd+F) without match case hide the f/F issue. Thanks to Kiran!

Upvotes: 0

Views: 75

Answers (1)

Awesome.Apple
Awesome.Apple

Reputation: 1324

It should be 

SEL callback = @selector(afterfollowAction:);
BOOL test1 = [self respondsToSelector:callback]; //NO
BOOL test2 = [self respondsToSelector:@selector(afterfollowAction:)]; //NO
BOOL test3 = [[self class] instanceMethodForSelector: @selector(afterfollowAction:)];  //YES
BOOL test4 = [self respondsToSelector:@selector(viewWillDisappear:)]; //YES
[self performSelector:callback withObject:nil]; //crash

Your are using capital "F"

Upvotes: 1

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