原文地址：http://www.cnblogs.com/gaoxiao228/archive/2012/05/04/2483577.html
label.transform = CGAffineTransformMakeRotation(90 *M_PI / 180.0);
//顺时针旋转 90度
label.transform = CGAffineTransformMakeRotation(180 *M_PI / 180.0);
//顺时针 旋转180度
label.transform = CGAffineTransformMakeRotation(270 *M_PI / 180.0);
//顺时针旋转270度
CGAffineTransform transform = label.transform;
transform = CGAffineTransformScale(transform, 2,0.5);//前面的2表示横向放大2倍，后边的0.5表示纵向缩小一半
label.transform = transform;
