iphone - 在子类 UIImageView 中，touchesBegan 触发，touchesMoved 触发几次，但随后无缘无故停止

Question

我已经子类化了 UIImageView，并实现了 TouchBegan/Moved/Finished，如下所示:

- (void)touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event {
NSLog(@"Began");

mouseSwiped = NO;
UITouch *touch = [touches anyObject];

if ([touch tapCount] == 2) {
    self.image = nil;
    return;
}

lastPoint = [touch locationInView:self];
lastPoint.y -= 20;

}




- (void)touchesMoved:(NSSet *)touches withEvent:(UIEvent *)event {
    mouseSwiped = YES;
        NSLog(@"Moved");
    UITouch *touch = [touches anyObject];   
    CGPoint currentPoint = [touch locationInView:self];
    currentPoint.y -= 20;


    UIGraphicsBeginImageContext(self.bounds.size);

    [self.image drawInRect:CGRectMake(0, 0, self.bounds.size.width, self.bounds.size.height)];
    CGContextSetLineCap(UIGraphicsGetCurrentContext(), kCGLineCapRound);
    CGContextSetLineWidth(UIGraphicsGetCurrentContext(), 18.0);
    CGContextSetRGBStrokeColor(UIGraphicsGetCurrentContext(), 0.0, 0.5, 1.0, 1.0);
    CGContextBeginPath(UIGraphicsGetCurrentContext());
    CGContextMoveToPoint(UIGraphicsGetCurrentContext(), lastPoint.x, lastPoint.y);
    CGContextAddLineToPoint(UIGraphicsGetCurrentContext(), currentPoint.x, currentPoint.y);
    CGContextStrokePath(UIGraphicsGetCurrentContext());
    self.image = UIGraphicsGetImageFromCurrentImageContext();
    UIGraphicsEndImageContext();

    lastPoint = currentPoint;

}

- (void)touchesEnded:(NSSet *)touches withEvent:(UIEvent *)event {
        NSLog(@"Ended");
    UITouch *touch = [touches anyObject];

    if ([touch tapCount] == 2) {
        self.image = nil;
        return;
    }


    if(!mouseSwiped) {
        NSLog(@"here?");
        UIGraphicsBeginImageContext(self.bounds.size);
        [self.image drawInRect:CGRectMake(0, 0, self.bounds.size.width, self.bounds.size.height)];
        CGContextSetLineCap(UIGraphicsGetCurrentContext(), kCGLineCapRound);
        CGContextSetLineWidth(UIGraphicsGetCurrentContext(), 18.0);
        CGContextSetRGBStrokeColor(UIGraphicsGetCurrentContext(), 0.0, 0.5, 1.0, 1.0);
        CGContextMoveToPoint(UIGraphicsGetCurrentContext(), lastPoint.x, lastPoint.y);
        CGContextAddLineToPoint(UIGraphicsGetCurrentContext(), lastPoint.x, lastPoint.y);
        CGContextStrokePath(UIGraphicsGetCurrentContext());
        CGContextFlush(UIGraphicsGetCurrentContext());
        self.image = UIGraphicsGetImageFromCurrentImageContext();
        UIGraphicsEndImageContext();
    }
}

它似乎在最初的一段时间内发挥了作用。 TouchesBegan() 每次都会触发，然后当我开始移动时，touchesMoved() 有时会触发 5 次，有时 3 次，有时 7 次，但然后就停止了。 touchesEnded() 永远不会被触发，我只是不知道发生了什么!

我已经盯着这个有一段时间了，有人看到我错过了什么吗？

Answer 1

重写并实现:- (void)touchesCancelled:(NSSet *)touches withEvent:(UIEvent *)event

看看是否正在调用。

如果是这样，则说明某些东西正在取消您的触摸事件。可能是内存不足。