Question

i´ve made lots of my own “CustomUIButton” in a for-loop in my viewcontroller.
In this “CustomUIButton”-class i´ve implemented an UIGestureRecognizer like this:

    (id)initWithFrame:(CGRect)frame 
    {
        self = [super initWithFrame:frame];
        if (self) {

    // custom things.

     UILongPressGestureRecognizer* longPress = [[UILongPressGestureRecognizer alloc] initWithTarget:self action:@selector(handleLongPress:)];
            longPress.minimumPressDuration = 1.0;
            [self addGestureRecognizer:longPress];
            [longPress release];
    }
}

    - (void) handleLongPress:(UILongPressGestureRecognizer*) recognizer{

        if (recognizer.state == UIGestureRecognizerStateEnded) {
            NSLog(@"Long press Ended");
        }
        else {

            NSLog(@"Long press detected.");
             // Do something
        }
    }

If i init the target with “self”, my “handleLongPress”-function in this class will be called. It´s cool. If i init the target with “nil”, it should check the parent viewcontroller, right?

Any ideas why an additional function with the same name in my viewcontroller won´t be called? (For this test i´ve commented the “longpress”-function of the button-class out.)

Answer 1

In the docs for UIGestureRecognizer’s initWithTarget:action: method, for the target parameter it says:

An object that is the recipient of
action messages sent by the receiver
when it recognizes a gesture. nil is
not a valid value.

Note the last sentence.

The docs also say this which should explain why it doesn’t work:

A gesture recognizer does not
participate in the view’s responder
chain.

You must specify a value for target.