Get the top UIWindow as seen in KLCPopup (https://github.com/jmascia/KLCPopup)

gistfile1.txt

// Prepare by adding to the top window.
if(!self.superview){
NSEnumerator *frontToBackWindows = [[[UIApplication sharedApplication] windows] reverseObjectEnumerator];

for (UIWindow *window in frontToBackWindows) {
  if (window.windowLevel == UIWindowLevelNormal) {
    [window addSubview:self];
    
    break;
  }
}
}