UIControlEventTouchDragExit triggers when 100 pixels away from UIButton
cocoa-touch, drag-and-drop, ios, objective-c, uitouch
Solution
Override continueTrackingWithTouch:withEvent: like this to send DragExit/DragOutside events inside of the default gutter:
- (BOOL)continueTrackingWithTouch:(UITouch *)touch withEvent:(UIEvent *)event
{
CGFloat boundsExtension = 25.0f;
CGRect outerBounds = CGRectInset(self.bounds, -1 * boundsExtension, -1 * boundsExtension);
BOOL touchOutside = !CGRectContainsPoint(outerBounds, [touch locationInView:self]);
if(touchOutside)
{
BOOL previousTouchInside = CGRectContainsPoint(outerBounds, [touch previousLocationInView:self]);
if(previousTouchInside)
{
NSLog(@"Sending UIControlEventTouchDragExit");
[self sendActionsForControlEvents:UIControlEventTouchDragExit];
}
else
{
NSLog(@"Sending UIControlEventTouchDragOutside");
[self sendActionsForControlEvents:UIControlEventTouchDragOutside];
}
}
return [super continueTrackingWithTouch:touch withEvent:event];
}
Problem
At present, the `UIControlEventTouchDragExit` only triggers when I drag 100 pixels away from the button. I'd like to customize this behavior and bring that range in to around 25 pixels, but I'm relatively new to programming and have never needed to override / customize an in-built method like this. I've read in some other posts here that I'd need to subclass the `UIButton` (or perhaps even `UIControl`?), and override `-(BOOL) beginTrackingWithTouch: (UITouch *) touch withEvent: (UIEvent *) event` and related methods, but I don't really know where to begin doing so. Could anyone kindly offer some advice as to how I might achieve this? Much appreciated! ^_^