CODEWITHSUNDEEP
iphoneobjective-c
Snowman
Snowman

Reputation: 32061

Detecting when UIButton event is done

I'm trying to implement a drag & drop feature on a UIButton, and it works fine, but I can't figure out a way to determine when the user has let go of the button and finished dragging. The below code works fine for dragging, but I need to be notified when the user has finished dragging and let go of the button.

- (void)viewDidLoad
{
    [gesturesBrowserButton addTarget:self action:@selector(wasDragged:withEvent:) 
     forControlEvents:UIControlEventTouchDragInside];

    [gesturesBrowserButton addTarget:self action:@selector(finishedDragging:withEvent:) 
                    forControlEvents:UIControlEventTouchDragExit];
}

- (void)wasDragged:(UIButton *)button withEvent:(UIEvent *)event
{
    // get the touch
    UITouch *touch = [[event touchesForView:button] anyObject];

    // get delta
    CGPoint previousLocation = [touch previousLocationInView:button];
    CGPoint location = [touch locationInView:button];
    CGFloat delta_x = location.x - previousLocation.x;
    CGFloat delta_y = location.y - previousLocation.y;

    // move button
    button.center = CGPointMake(button.center.x + delta_x,
                                button.center.y + delta_y);

    NSLog(@"was dragged");
}

- (void)finishedDragging:(UIButton *)button withEvent:(UIEvent *)event
{
    //doesn't get called
    NSLog(@"finished dragging");
}

Upvotes: 3

Views: 1652

Answers (2)

mvds
mvds

Reputation: 47034

I think that replacing

UIControlEventTouchDragExit

with

UIControlEventTouchDragExit|UIControlEventTouchUpInside

would be a good start to solve your problem.

Upvotes: 11

Rob Napier
Rob Napier

Reputation: 299265

The event I believe you want here is UIControlEventTouchUpInside. That's the "touch has gone away while inside this control." It's possible you won't get that one at this point, though. You certainly won't get UIControlEventTouchDragExit, since that means the drag has left the control.

If UIControlEventTouchUpInside doesn't work for you, I like to capture UIControlEventAllEvents and just log them as they come in. Then you can see exactly what is fired when.

Upvotes: 2

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