Question

I’ve subclassed a UIView as an avatar-object, which contains an icon (UIImageView), name (UILabel) and ID (UILabel). Depending on the orientation X,Y coordinates, I want the icon to be rotated. For example, say orientation.X = 1 and orientation.Y = 1 would give 45 degrees angle. X and Y could be anything between -1 and 1.

I’m not sure how it is calculated mathematically nor the cocoa API calls for it. Any ideas where to start?

Answer 1

for smoothness i added an animation:

- (void)rotateView:(UIView *)view withDuration:(NSTimeInterval)duration andRadians:(CGFloat)radians
{
    // Setup the animation
    [UIView beginAnimations:nil context:NULL];
    [UIView setAnimationDuration:duration];
    [UIView setAnimationCurve:UIViewAnimationCurveEaseOut];
    [UIView setAnimationBeginsFromCurrentState:YES];

    // The transform matrix
    CGAffineTransform transform = CGAffineTransformMakeRotation(radians);
    view.transform = transform;

    // Commit the changes
    [UIView commitAnimations];

}

EDIT:

for other angles you need to create your own rotation matrix.

How rotation matrix works

Read here how to create a custom affine transformation in Objective-c

Hope this helps.