UIButton changes image created in code when in highlighted state - ios

Question

I have two buttons. They both have the same image except the fact that one of the images is flipped. I don't want to have an excess image in the bundle of my app if it's possible to create image programmatically so i create my buttons like this:
UIImage *forwardImage = [UIImage imageNamed:rewind_btn_img];
UIImage *rewindImage = [UIImage imageWithCGImage:forwardImage.CGImage
scale:forwardImage.scale
orientation:UIImageOrientationUpMirrored];
NSArray *images = #[rewindImage, forwardImage];
for (int i = 0; i < 2; i++)
{
UIButton *btn = [UIButton buttonWithType:UIButtonTypeCustom];
UIImage *image = images[i];
btn.frame = CGRectMake(0.f, 0.f, image.size.width, image.size.height);
btn.center = CGPointMake(self.playButton.center.x + (i == 0 ? - 80.f : 80.f) * TGScaleMultiplier, self.playButton.center.y);
btn.tag = i + 1;
[btn setBackgroundImage:image forState:UIControlStateNormal];
[btn addTarget:self action:#selector(rewindButtonClicked:) forControlEvents:UIControlEventTouchUpInside];
[self.view addSubview:btn];
}
The problem is that when i press the button whose image is rewindImage it shows the original image, flipped to the other side. Am i doing something incorrectly here? Is there any workaround?

Answer 1

Not sure exactly why that UIImage:imageWithCGImage is flaky but I tried another method for mirroring the image and when applied to the button it works great. So get rid of the UIImage:imageWithCGImage line and use this:
UIImage *rewindImageBase = [UIImage imageNamed:rewind_btn_img];
UIGraphicsBeginImageContext(rewindImageBase.size);
CGContextRef current_context = UIGraphicsGetCurrentContext();
CGContextTranslateCTM(current_context, rewindImageBase.size.width, 0);
CGContextScaleCTM(current_context, -1.0, 1.0);
[rewindImageBase drawInRect:CGRectMake(0, 0, rewindImageBase.size.width, rewindImageBase.size.height)];
UIImage *rewindImage = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
That should do it.

Answer 2

if it initially looks right, but changes when you press it, Try setting the image for all button states, or at least for the normal state and the selected state.
[btn setBackgroundImage:image forState:UIControlStateNormal];
[btn setBackgroundImage:image forState:UIControlStateSelected];
you could also try setting the showsTouchWhenHighlited but the first way should work
[btn setShowsTouchWhenHighlighted:NO];
EDIT: try also setting the highlighted state, this works for me
[btn setBackgroundImage:image forState:UIControlStateHighlighted];