视图的缩小放大，旋转，平移

//view原始的transform

CGAffineTransform transform = view.transform;

//缩放

//在原来的基础上缩放0.5倍

view.transform = CGAffineTransformScale(transform, 0.5, 0.5);

//旋转

view.transform = CGAffineTransformRotate(view.transform, M_PI/4);

//平移

view.transform = CGAffineTransformTranslate(view.transform, -50, -50);

//还原为初始的transform

view.transform = CGAffineTransformIdentity;