iphone - 如何使用 UIPanGestureRecognizer 移动对象？ iPhone/iPad

Question

UIPanGestureRecognizer 类有几个示例。例如我读过 this而且我仍然无法使用它...

在我正在处理的 nib 文件上，我有一个 UIView(图像上的白色矩形)，我希望用该类拖动它:

在我放置的 .m 文件中:

- (void)setTranslation:(CGPoint)translation inView:(UIView *)view
{
    NSLog(@"Test to see if this method gets executed");
}

当我将鼠标拖过 UIView 时，该方法不会被执行。我也试过放置:

- (void)pan:(UIPanGestureRecognizer *)gesture
{
    NSLog(@"testing");
}

而且该方法也不会被执行。也许我错了，但我认为这些方法应该像 - (void) touchesMoved:(NSSet *)touches withEvent:(UIEvent *)event 方法一样工作，我只需要放置该方法，它就会每当有触摸时都会被调用。

我做错了什么？也许我必须与该方法建立联系？如果是这样，我该怎么做？

Answer 1

我找到了教程 Working with UIGestureRecognizers ，我认为这就是我要找的。它帮助我想出了以下解决方案:

-(IBAction) someMethod {
    UIPanGestureRecognizer *panRecognizer = [[UIPanGestureRecognizer alloc] initWithTarget:self action:@selector(move:)];
    [panRecognizer setMinimumNumberOfTouches:1];
    [panRecognizer setMaximumNumberOfTouches:1];
    [ViewMain addGestureRecognizer:panRecognizer];
    [panRecognizer release];
}

-(void)move:(UIPanGestureRecognizer*)sender {
    [self.view bringSubviewToFront:sender.view];
    CGPoint translatedPoint = [sender translationInView:sender.view.superview];

    if (sender.state == UIGestureRecognizerStateBegan) {
        firstX = sender.view.center.x;
        firstY = sender.view.center.y;
    }


    translatedPoint = CGPointMake(sender.view.center.x+translatedPoint.x, sender.view.center.y+translatedPoint.y);

    [sender.view setCenter:translatedPoint];
    [sender setTranslation:CGPointZero inView:sender.view];

    if (sender.state == UIGestureRecognizerStateEnded) {
        CGFloat velocityX = (0.2*[sender velocityInView:self.view].x);
        CGFloat velocityY = (0.2*[sender velocityInView:self.view].y);

        CGFloat finalX = translatedPoint.x + velocityX;
        CGFloat finalY = translatedPoint.y + velocityY;// translatedPoint.y + (.35*[(UIPanGestureRecognizer*)sender velocityInView:self.view].y);

        if (finalX < 0) {
            finalX = 0;
        } else if (finalX > self.view.frame.size.width) {
            finalX = self.view.frame.size.width;
        }

        if (finalY < 50) { // to avoid status bar
            finalY = 50;
        } else if (finalY > self.view.frame.size.height) {
            finalY = self.view.frame.size.height;
        }

        CGFloat animationDuration = (ABS(velocityX)*.0002)+.2;

        NSLog(@"the duration is: %f", animationDuration);

        [UIView beginAnimations:nil context:NULL];
        [UIView setAnimationDuration:animationDuration];
        [UIView setAnimationCurve:UIViewAnimationCurveEaseOut];
        [UIView setAnimationDelegate:self];
        [UIView setAnimationDidStopSelector:@selector(animationDidFinish)];
        [[sender view] setCenter:CGPointMake(finalX, finalY)];
        [UIView commitAnimations];
    }
}