How to stop UIPanGestureRecognizer when object moved to certain frame

问题

I have an object of image type which I am moving using UIPanGestureRecognizer, and I need to stop recognizing the UIPanGestureRecognizer when the object reaches a certain frame.

    UIPanGestureRecognizer *panRecognizer = [[UIPanGestureRecognizer alloc] initWithTarget:self action:@selector(move:)];
    [panRecognizer setMinimumNumberOfTouches:1];
    [panRecognizer setMaximumNumberOfTouches:1];
    [panRecognizer setDelegate:self];
    [templatePhotoPlaceholderView addGestureRecognizer:panRecognizer];

-(void)move:(UIPanGestureRecognizer *)gestureRecognizer
{
    CGPoint translatedPoint = [gestureRecognizer translationInView:templatePhotoPlaceholderView];

    if([gestureRecognizer state] == UIGestureRecognizerStateBegan) {
        _firstX = [imageview center].x;
        _firstY = [imageview center].y;
    }



    translatedPoint = CGPointMake(_firstX+translatedPoint.x, _firstY+translatedPoint.y);
    //NSLog(@" Move center point :%@", NSStringFromCGPoint(translatedPoint));

    [imageview setCenter:translatedPoint];  

}

How may I do this ?

回答1:

UIGestureRecognizers have an enabled property. Documentation:

Disables a gesture recognizers so it does not receive touches. The default value is YES. If you change this property to NO while a gesture recognizer is currently recognizing a gesture, the gesture recognizer transitions to a cancelled state.

EDIT:

Just set the enabled property to NO.

gestureRecognizer.enabled = NO;

回答2:

When you need to stop your UIPanGestureRecognizer from recognizing gesture, you just put this code line (as jbat100 said) in -(void)move:(UIPanGestureRecognizer *)gestureRecognizer:

gestureRecognizer.enabled = NO;

after this line your gestureRecognizer state set as "UIGestureRecognizerStateCancelled"

then just add couple lines to your -(void)move:(UIPanGestureRecognizer *)gestureRecognizer function:

if ([gestureRecognizer state] == UIGestureRecognizerStateCancelled) {
     gestureRecognizer.enabled = YES;
}

and you'll be able to work with your gesture recognizer

EDIT:

Here's code snippet:

- (void)move:(UIPanGestureRecognizer *)gestureRecognizer {
    BOOL cancelPanGesture = YES;
    if (cancelPanGesture) {
        /* 
         After this line gesture recognizer will be disabled, state will be UIGestureRecognizerStateCancelled
         and this method (move:) will fire one more time.
         */
        gestureRecognizer.enabled = NO;
    }
    if (gestureRecognizer.state == UIGestureRecognizerStateCancelled) {
        gestureRecognizer.enabled = YES;
    }
}

回答3:

Set the pangesture.delegate=self, and implement delegate method

- (BOOL)gestureRecognizerShouldBegin:(UIGestureRecognizer *)gestureRecognizer
{
     //return NO when you reach the frame
}

来源：https://stackoverflow.com/questions/8078780/how-to-stop-uipangesturerecognizer-when-object-moved-to-certain-frame

标签

iphone

objective-c

ipad

uigesturerecognizer

uipangesturerecognizer