pinchGes= [[UIPinchGestureRecognizeralloc]initWithTarget:selfaction:@selector(pinchAct:)];
[imageVIewaddGestureRecognizer:pinchGes];
和uitapgesturerecognizer一样
触发的函数会有参数有一个scale属性缩放比例
//p1:原来的矩阵,p2：x方向的缩放比例，p3:y方向的缩放比例
//返回值是新的transform
pinch.view.transform=CGAffineTransformScale(pinch.view.transform,pinch.scale,pinch.scale);
//缩放完后把事件的缩放比例归位不然会累加
pinch.scale=1;
