Create highlighted state background image programmatically for UIButton - iphone

Question

I created a UIBarButton programmatically with the following code:
UIButton * rightButton = [UIButton buttonWithType:UIButtonTypeCustom];
[rightButton setFrame:CGRectMake(0, 0, 81, 30)];
[rightButton setBackgroundColor:[UIColor clearColor]];
rightButton.layer.borderColor = [UIColor blackColor].CGColor;
rightButton.layer.borderWidth = 0.5f;
rightButton.layer.cornerRadius = 5.0f;
rightButton.titleLabel.font = [UIFont fontWithName:#"HelveticaNeue-Bold" size:12];
[rightButton setTitleShadowColor:[UIColor blackColor] forState:UIControlStateNormal];
[rightButton setTitleColor:[UIColor whiteColor] forState:UIControlStateNormal];
//set text according to sign in status
if (signIn) {
[rightButton setTitle:#"5 votes left" forState:UIControlStateNormal];
} else {
[rightButton setTitle:#"Sign in" forState:UIControlStateNormal];
}
UIBarButtonItem * rightBarButton = [[UIBarButtonItem alloc] initWithCustomView:rightButton];
self.navigationItem.rightBarButtonItem = rightBarButton;
The obtained button has the desired aspect but now what I need is that when the status of the button is highlighted there should be a gradient effect fading to black to let the user know that he has pressed the button, because right now when I pressed the button, nothing happens to the view so the user has no way to know that he has pressed the button.
I want to explore a choice that does NOT involve setting the background images for the desired states because the text of the button can change dynamically according to the app configurations so I need to do this entirely by code.

Answer 1

Although this won't directly answer your question, it may help. I had to create some graphics for a button dynamically and came up with a method using core graphics to create my button image. It gives me the flexibility to change to appearance parametrically in the code.It draws the button image in an abstract graphics context and then converts the result into an image that I can use for my button. YOu might get enough out of my explanation that you can try it yourself for your needs.

Answer 2

Subclass UIButton and add a CALayer or CAGradientLayer to achieve the highlight effect that you want. Set the initial state of the highlight layer to hidden. Override setHighlighted: with something like:
- (void) setHighlighted:(BOOL)highlight {
highlightLayer.hidden = !highlight;
[super setHighlighted:highlight];
}