title: How to set selected image of UIButton in XCode Interface Builder
body: <p>I have two image sets for "flag" button in my Images.xcassets: flag-highlighted and flag-normal, where each set has 3 images of size x1, x2, x3</p>
  
  <p>I use the flag-normal image set for the Image attribute in the attributes inspector for this button.  But, where/how do I specify the flag-highlighted image set for the selected state?</p>