transform本质上是改变了控件的frame
transform基本设置
// 缩放
self.tempView.transform = CGAffineTransformMakeScale(0.5, 0.5);
// 平移
self.tempView.transform = CGAffineTransformMakeTranslation(-100, 100);
//旋转
self.tempView.transform = CGAffineTransformMakeRotation(-M_PI_4);
transform属性的叠加
CGAffineTransform translation = CGAffineTransformMakeTranslation(-100, 100);
CGAffineTransform scaleTranslation = CGAffineTransformScale(translation, 0.5, 0.5);
CGAffineTransform rotateScaleTranslation = CGAffineTransformRotate(scaleTranslation, M_PI_2);
self.tempView.transform = rotateScaleTranslation;
清空transform，以前的平移、缩放、旋转都会消失
self.tempView.transform = CGAffineTransformIdentity;
