检测旋转手势和缩放手势iphone sdk答案

【问题标题】：detect rotate gesture and scale gesture iphone sdk检测旋转手势和缩放手势iphone sdk
【发布时间】：2010-07-12 11:53:30
【问题描述】：

我想旋转 uiimageview 并缩放图像视图，那么我如何检测用户正在缩放或用户正在旋转的触摸手势？

【问题讨论】：

标签： iphone uiimageview touch

【解决方案1】：

从 iOS 3.2 开始，Apple 引入了UIGestureRecognizer 的使用。您会感兴趣的两个是UIPinchGestureRecognizer 和UIRotationGestureRecognizer。要使用捏合手势，您可以执行以下操作：

- (void)viewDidLoad {
    UIPinchGestureRecognizer *pinch = [[UIPinchGestureRecognizer alloc] initWithTarget:self action:@selector(handlePinchGesture:)];
    [imageView addGestureRecognizer:pinch];
    [pinch release];
}

- (void)handlePinchGesture:(UIGestureRecognizer *)sender {
    NSLog(@"New Scale: %f", sender.scale);
}

你可以为UIRotationGestureRecognizer 做类似的事情。

【讨论】：

NSLog(@"New Scale: %f", sender.scale);它在编译时也会出错，像这样“错误：在非结构或联合的东西中请求成员‘规模’”
我想在不使用 UIGestureRecognizer 的情况下做到这一点，有没有办法在 touchMoved 上做到这两点？
在touchMoved中可以做，但是会比较复杂。您将需要获取触摸的位置并为这些触摸创建一个边界框。然后您可以根据该边界矩形缩放图像视图。
你能告诉我怎么做吗？这可能很复杂，但并非不可能......

【解决方案2】：

在你的 viewcontroller.h 文件中写下这个属性

IBOutlet UIImageView *imgRotate;
CGFloat lastScale;
CGFloat lastRotation;

现在在您的 viewcontroller.m 文件中写入以下代码，

- (void)viewDidLoad
{
[super viewDidLoad];
// Do any additional setup after loading the view from its nib.

UIPinchGestureRecognizer *pinchRecognizer = [[UIPinchGestureRecognizer alloc] initWithTarget:self action:@selector(scale:)];
[pinchRecognizer setDelegate:self];
[imgRotate addGestureRecognizer:pinchRecognizer];

UIRotationGestureRecognizer *rotationRecognizer = [[UIRotationGestureRecognizer alloc] initWithTarget:self action:@selector(rotate:)];
[rotationRecognizer setDelegate:self];
[imgRotate addGestureRecognizer:rotationRecognizer];
}

-(void)scale:(id)sender
{
if([(UIPinchGestureRecognizer*)sender state] == UIGestureRecognizerStateEnded)
{
    lastScale = 1.0;
    return;
}

CGFloat scale = 1.0 - (lastScale - [(UIPinchGestureRecognizer*)sender scale]);

CGAffineTransform currentTransform = [(UIPinchGestureRecognizer*)sender view].transform;
CGAffineTransform newTransform = CGAffineTransformScale(currentTransform, scale, scale);

[[(UIPinchGestureRecognizer*)sender view] setTransform:newTransform];

[imgRotate setTransform:newTransform];
lastScale = [(UIPinchGestureRecognizer*)sender scale];
}

-(void)rotate:(id)sender
{
if([(UIRotationGestureRecognizer*)sender state] == UIGestureRecognizerStateEnded)
{
    lastRotation = 0.0;
    return;
}

CGFloat rotation = 0.0 - (lastRotation - [(UIRotationGestureRecognizer*)sender rotation]);

CGAffineTransform currentTransform = [(UIPinchGestureRecognizer*)sender view].transform;
CGAffineTransform newTransform = CGAffineTransformRotate(currentTransform,rotation);

[[(UIRotationGestureRecognizer*)sender view] setTransform:newTransform];

[imgRotate setTransform:newTransform];
lastRotation = [(UIRotationGestureRecognizer*)sender rotation];
}

-(void)touchesMoved:(NSSet *)touches withEvent:(UIEvent *)event
{
UITouch *touch = [touches anyObject];

if ([touch view] == imgRotate) {
    CGPoint location = [touch locationInView:self.view];
    imgRotate.center = location;
}
}

【讨论】：