Designing Graphics

Use a 10px rounded corner for iPhone and iPad button graphics if you want to match the standard button shape.

If not set the button 'Type' to 'Custom' so that is become transparent other than your image.

Dealing with iPhone4 vs iPhone3 resolutions

You can list any image as [email protected] along with Image.png and the system will select the appropriate image at runtime.

Different Button Option On / Off Images

Select the button in the .xib and use the 'State Config' setting.  Set one image name for 'Default' and another for 'Selected'.  Then alter the selected property in your code like this:

- (IBAction) MyButtonPressed:(UIButton*) sender
    sender.selected = !sender.selected;

or like this

    self.MyButton.selected = NO;

Multiple buttons can be set to different selected states (selected isn't a single control based thing).

Button Is Blue in iOS7

Change the button from type "System" to "Custom"