UIImage iPhone Rotate 37.8 degrees

Question

After I load an image from the device, I need to rotate it 37.8 degrees then display it on a View.

Is there an function in Objective-C that can do the image rotation?

Ian

Answer 1

Yes, see my answer to this question: http://stackoverflow.com/questions/1999309/question-about-rotating-a-slider/1999389#1999389

To convert degrees to radians (for the positionInRadians arg) use this function:

CGFloat DegreesToRadians(CGFloat degrees) {return degrees * M_PI / 180;};

Answer 2

To rotate the view:

imageView.transform = CGAffineTransformMakeRotation(37.8°);

To rotate the image,

1. Calculate the width and height will be occupied by the image after rotation.
2. Create a CGContext by UIGraphicsBeginImageContext.
3. CGContextRotateCTM(UIGraphicsGetCurrentContext(), 37.8°);
4. [yourImage drawAtPoint:...];
5. UIGraphicsGetImageFromCurrentImageContext(); and use this image instead.
6. Release the context.