In my experiment, i conclude these:
YourView.transform = CGAffineTransformMakeRotation( positive value );
will rotate the view clockwise, and
YourView.transform = CGAffineTransformMakeRotation( Negative value );
will rotate the view counterclockwise,
But the document says:
The angle, in radians, by which to rotate the affine transform. In iOS, a positive value specifies counterclockwise rotation and a negative value specifies clockwise rotation.
does those contradict with each other?