Can I pass a block as a @selector with Objective-C?

Question

Is it possible to pass an Objective-C block for the @selector argument in a UIButton? i.e., Is there any way to get the following to work?

Answer 1

Doesn't it work to have an NSBlockOperation (iOS SDK +5). This code uses ARC and it is a simplification of an App I am testing this with (seems to work, at least apparently, not sure if I am leaking memory).

NSBlockOperation *blockOp;
UIView *testView; 

-(void) createTestView{
    UIView *testView = [[UIView alloc] initWithFrame:CGRectMake(0, 60, 1024, 688)];
    testView.backgroundColor = [UIColor blueColor];
    [self.view addSubview:testView];            

    UIButton *btnBack = [UIButton buttonWithType:UIButtonTypeRoundedRect];
    [btnBack setFrame:CGRectMake(200, 200, 200, 70)];
    [btnBack.titleLabel setText:@"Back"];
    [testView addSubview:btnBack];

    blockOp = [NSBlockOperation blockOperationWithBlock:^{
        [testView removeFromSuperview];
    }];

    [btnBack addTarget:blockOp action:@selector(start) forControlEvents:UIControlEventTouchUpInside];
}

Of course, I am not sure how good this is for real usage. You need to keep a reference to the NSBlockOperation alive or I think that ARC will kill it.

Answer 2

The library BlocksKit on Github (also available as a CocoaPod) has this feature built-in.

Take a look at the header file for UIControl+BlocksKit.h. They've implemented Dave DeLong's idea so you don't have to. Some documentation is here.

Answer 3

No, selectors and blocks are not compatible types in Objective-C (in fact, they're very different things). You'll have to write your own method and pass its selector instead.