等比例放大+手势识别

最近学习了下手势操作，尤其是对缩放的研究，先记录下，
UIPinchGestureRecognizer主要是用来对图片或者对其它view进行缩放的。
- （void）viewdidload{
UIPinchGestureRecognizer *pinchRecognizer = [[[UIPinchGestureRecognizer alloc] initWithTarget:self action:@selector(scale:)] autorelease];
    [pinchRecognizer setDelegate:self];//需要在头文件中引入UIGestureRecognizerDelegate
    [self.pieChartLeft addGestureRecognizer:pinchRecognizer];
}
#pragma mark - UIGestureRecognizerDelegate Methods
- (void)scale:(UIPinchGestureRecognizer *)gestureRecognizer{
    if ([gestureRecognizer state] == UIGestureRecognizerStateBegan || [gestureRecognizer state] == UIGestureRecognizerStateChanged) {
        int width = [gestureRecognizer view].frame.size.width;
        if ([gestureRecognizer scale]>1.f&&width<320) {
            [UIView animateWithDuration:1.f animations:^(void){
                                                        [gestureRecognizer view].transform = CGAffineTransformScale([[gestureRecognizer view] transform], 2.0, 2.0); 
                                                        }];
          
        } else if ([gestureRecognizer scale]<1.f&&width>174) {
            [UIView animateWithDuration:1.f animations:^(void){
                                                        [gestureRecognizer view].transform = CGAffineTransformScale([[gestureRecognizer view] transform], 0.5, 0.5);
            }];
        }
        [gestureRecognizer setScale:1];
    }
}
其中这个scale我是写死的，因为我的需求是手指捏合的时候回到原始大小，放大的时候全屏大小，如果想随着手指的分开和捏合来不断改变的话，借用官方的文档的写法，应该是：
if ([gestureRecognizer state] == UIGestureRecognizerStateBegan || [gestureRecognizer state] == UIGestureRecognizerStateChanged) {
        [gestureRecognizer view].transform = CGAffineTransformScale([[gestureRecognizer view] transform], [gestureRecognizer scale], [gestureRecognizer scale]);
        [gestureRecognizer setScale:1];
    }
这个1相当于原始大小，如果[gestureRecognizer scale]的值小于1表示两手指间的距离在不断地缩小，大于1表示两手指间的距离不断地变大，
另外需要说明的是我写死的这个scale，它是指的是，当前的视图的大小和你想要变化之后视图的大小的比例