CGAffineTransform旋转UIButton

Question

I have a UIButton. On this button I apply a CGAffineTransform like this:

_mainButton.transform = CGAffineTransformMakeRotation((degrees-heading.trueHeading) * M_PI / 180);

In this way I can rotate all my buttons, but I would like to rotate only the background image.

So, myButton.imageView should remain at its fixed location. How can make this?

Answer 1

You have to rotate the imageView property of the UIButton like this:

_mainButton.imageView.transform = CGAffineTransformMakeRotation((degrees-heading.trueHeading) * M_PI / 180);

imageView The button's image view. (read-only)

@property(nonatomic, readonly, retain) UIImageView *imageView

Discussion

Although this property is read-only, its own properties are read/write. Use these properties to configure the appearance and behavior of the button's view. For example:

UIButton *button                   = [UIButton buttonWithType: UIButtonTypeSystem];
button.imageView.exclusiveTouch    = YES;

The imageView property returns a value even if the button has not been displayed yet. The value of the property is nil for system buttons.

It's directly from Apple's documentation

Answer 2

Try this, works well:

- (IBAction)toggle:(UIButton *)sender {
[UIView animateWithDuration:0.2 animations:^{
    if (CGAffineTransformEqualToTransform(sender.transform, CGAffineTransformIdentity)) {
        sender.transform = CGAffineTransformMakeRotation(M_PI * 0.999);
    } else {
        sender.transform = CGAffineTransformIdentity;
    }
}];

}