It could be probably a bug on iOS7. But the last button is not separated from the previous one
The simplest fix is to pass @""
to the cancel button title instead of nil
during allocation.
UIActionSheet *actionSheet = [[UIActionSheet alloc]
initWithTitle:@"Title"
delegate:self
cancelButtonTitle:@"" // change is here
destructiveButtonTitle:nil
otherButtonTitles:@"First", @"Second", @"Third", @"Fourth", nil];
[actionSheet showInView:self.view];