IPhone開發文檔經典語句

1:When a touch occurs inside a specific view, the system sends an event object with the touch information directly to that view for handling. However, if the view does not handle a particular touch event, it can pass the event object along to its superview. If the superview does not handle the event, it passes the event object to its superview, and so on up the responder chain

測試:

- (void)viewDidLoad
{
    [super viewDidLoad];
    
    UIView * view = [[UIView alloc]initWithFrame:CGRectMake(0, 0, 320, 480)];
    view.backgroundColor = [UIColor blueColor];
    
    UITapGestureRecognizer * tapGesture = [[UITapGestureRecognizer alloc]initWithTarget:self action:@selector(viewClick:)];
    
    [view addGestureRecognizer:tapGesture];
    
    UIView * view2 = [[UIView alloc]initWithFrame:CGRectMake(0, 0, 100, 100)];
    view2.center = CGPointMake(self.view.frame.size.width/2.0, self.view.frame.size.height/2.0);
    view2.backgroundColor = [UIColor blackColor];
    [self.view addSubview:view];
    
    
    UIButton * button = [[UIButton alloc]initWithFrame:CGRectMake(0, 0, 60, 50)];
    button.backgroundColor = [UIColor redColor];
    [button addTarget:self action:@selector(buttonClick) forControlEvents:UIControlEventTouchUpInside];
    button.center = CGPointMake(self.view.frame.size.width/2.0, self.view.frame.size.height/2.0);
    [view addSubview:button];
    [view addSubview:view2];
}

- (void)buttonClick
{
    NSLog(@"buttonClick");
}

- (void)viewClick:(UITapGestureRecognizer *)tap
{
    int red =arc4random()%255;
    int green = arc4random()%255;
    int blue = arc4random()%255;
    NSLog(@"%d %d %d",red,green,blue);
    tap.view.backgroundColor = [UIColor colorWithRed:red/255.0 green:green/255.0 blue:blue/255.0 alpha:1];
}

測試發現在view2上發生點擊事件,由于view2并不響應該事件,于是將事件傳遞給它的父視圖,顏色發生改變,但是該點擊事件并不會通過view2傳遞給button,所以事件傳遞,僅傳遞給它的父視圖,也就是[superview addsubview:subview]中得superview