Objective-C：当手指仍在屏幕上时识别滑动手势

Question

我的屏幕上有图像视图，我想要检测，当用户从左到右和从右到左不停止滑动此图像时。当他这样做时，他的手指仍然在屏幕上。我想要的每次滑动都添加到我的swipeCount变量中。 我试过这个：

- (void)touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event {
    UITouch *touch = [touches anyObject];
    self.startPosition = [touch locationInView:self.imageView];
}

- (void)touchesEnded:(NSSet *)touches withEvent:(UIEvent *)event {
    UITouch *touch = [touches anyObject];
    CGPoint endPosition = [touch locationInView:self.imageView];
    if (self.startPosition.x != endPosition.x || self.startPosition.y != endPosition.y) {
        self.swipeCount++;
        self.labelSwipeCount.text = [NSString stringWithFormat:@"%d", self.swipeCount];
    }
}

但是如果用户没有超出图像范围，那么touchesEnded不起作用。我怎样才能实现自己的想法？