How can I tell a UIGestureRecognizer to cancel an existing touch?

Question

I have a UIPanGestureRecognizer I am using to track an object (UIImageView) below a user\'s finger. I only care about motion on the X axis, and if

Answer 1

According to the documentation you can subclass you gesture recogniser:

In YourPanGestureRecognizer.m:

#import "YourPanGestureRecognizer.h"

@implementation YourPanGestureRecognizer

- (void) cancelGesture {
    self.state=UIGestureRecognizerStateCancelled;
}

@end

In YourPanGestureRecognizer.h:

#import 
#import 

@interface NPPanGestureRecognizer: UIPanGestureRecognizer

- (void) cancelGesture;

@end

Now you can call if from anywhere

YourPanGestureRecognizer *panRecognizer = [[YourPanGestureRecognizer alloc] initWithTarget:self action:@selector(panMoved:)];
[self.view addGestureRecognizer:panRecognizer];
[...]
-(void) panMoved:(YourPanGestureRecognizer*)sender {
    [sender cancelGesture]; // This will be called twice
}

Ref: https://developer.apple.com/documentation/uikit/uigesturerecognizer?language=objc