在这:
-(IBAction)buttonClick: (id)sender {
UIActionSheet *actionSheet = [[UIActionSheet alloc]
initWithTitle:@"Fo Sho?"
delegate:self
cancelButtonTitle:@"Cancel"
destructiveButtonTitle:@"fo sho"
otherButtonTitles:nil];
[actionSheet showInView:self.view];
}
UIButton 将链接到这个“buttonClick”IBAction,但什么是“self”?