How to rotate an image by some angle which is set by programmatically?

问题

Currently I am fetching a random image from the iPad image library and showing it in UIImageView. I want to rotate it by some predefined angle which I can set.

I don't want any touch based rotation. How can I do that?

回答1:

Why not just rotate the UIImageView? Include QuartzCore framework.

#import <QuartzCore/QuartzCore.h>

self.imageView.layer.affineTransform = CGAffineTransformMakeRotation(angle)

See the documentation on CGAffineTransformMakeRotation

回答2:

you can use this one:

CGAffineTransform newTransform = CGAffineTransformMakeRotation((CGFloat)(90 * M_PI / 180.0));

self.imageView.transform = newTransform;

Here 90 in degree, You can use another angle.

回答3:

CGAffineTransform rotateTransform = CGAffineTransformMakeRotation( DEGREES_TO_RADIANS( rotateValue ) );
myObject.transform = rotateTransform;

来源：https://stackoverflow.com/questions/8064200/how-to-rotate-an-image-by-some-angle-which-is-set-by-programmatically