체크 마크를 인식하는 UIGestureRecognizer 서브클래스

UICheckGestureRecognizer.m

#import <UIKit/UIGestureRecognizerSubclass.h>

 

// Implemented in your custom subclass

- (void)touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event {

    [super touchesBegan:touches withEvent:event];

    if ([touches count] != 1) {

        self.state = UIGestureRecognizerStateFailed;

        return;

    }

}

 

- (void)touchesMoved:(NSSet *)touches withEvent:(UIEvent *)event {

    [super touchesMoved:touches withEvent:event];

    if (self.state == UIGestureRecognizerStateFailed) return;

    UIWindow *win = [self.view window];

    CGPoint nowPoint = [touches.anyObject locationInView:win];

    CGPoint nowPoint = [touches.anyObject locationInView:self.view];

    CGPoint prevPoint = [touches.anyObject previousLocationInView:self.view];

 

    // strokeUp is a property

    if (!self.strokeUp) {

        // On downstroke, both x and y increase in positive direction

        if (nowPoint.x >= prevPoint.x && nowPoint.y >= prevPoint.y) {

            self.midPoint = nowPoint;

            // Upstroke has increasing x value but decreasing y value

        } else if (nowPoint.x >= prevPoint.x && nowPoint.y <= prevPoint.y) {

            self.strokeUp = YES;

        } else {

            self.state = UIGestureRecognizerStateFailed;

        }

    }

}

 

- (void)touchesEnded:(NSSet *)touches withEvent:(UIEvent *)event {

    [super touchesEnded:touches withEvent:event];

    if ((self.state == UIGestureRecognizerStatePossible) && self.strokeUp) {

        self.state = UIGestureRecognizerStateRecognized;

    }

}

 

- (void)touchesCancelled:(NSSet *)touches withEvent:(UIEvent *)event {

    [super touchesCancelled:touches withEvent:event];

    self.midPoint = CGPointZero;

    self.strokeUp = NO;

    self.state = UIGestureRecognizerStateFailed;

}