/* Returns a transform that rotates by 'angle' radians about the vector * '(x, y, z)'. If the vector has length zero the identity transform is * returned. */CA_EXTERN CATransform3D CATransform3DMakeRotation (CGFloat angle, CGFloat x, CGFloat y, CGFloat z) CA_AVAILABLE_STARTING (10.5, 2.0, 9.0, 2.0);
angle:旋转角度
后面的x,y,z三个值表示坐标系里面的一个点（x,y,z),原点与该点形成一条旋转轴