UIDynamicAnimator順序動畫

Question

我正在嘗試使按鈕從菜單按鈕中彈出（類似於Path上的+按鈕），並使用UIDynamicAnimator設置捕捉和退出按鈕的動畫。 它有效並且代碼非常簡單。

    _animator = [[UIDynamicAnimator alloc] initWithReferenceView:sender.superview];

    UIDynamicItemBehavior *resistance = [[UIDynamicItemBehavior alloc] initWithItems:@[_cartBtn, _chatBtn, _eventBtn]];
    resistance.resistance = 5.0f;
    [_animator addBehavior:resistance];

    CGFloat radius = 75;
    CGPoint target = sender.center;
    target.x += radius * cos(GLKMathDegreesToRadians(265));
    target.y += radius * sin(GLKMathDegreesToRadians(265));
    UISnapBehavior *snapBehavior = [[UISnapBehavior alloc] initWithItem:_cartBtn snapToPoint:target];
    [_animator addBehavior:snapBehavior];

    target = sender.center;
    target.x += radius * cos(GLKMathDegreesToRadians(225));
    target.y += radius * sin(GLKMathDegreesToRadians(225));
    UISnapBehavior *snapBehavior2 = [[UISnapBehavior alloc] initWithItem:_chatBtn snapToPoint:target];
    [_animator addBehavior:snapBehavior2];

    target = sender.center;
    target.x += radius * cos(GLKMathDegreesToRadians(185));
    target.y += radius * sin(GLKMathDegreesToRadians(185));
    UISnapBehavior *snapBehavior3 = [[UISnapBehavior alloc] initWithItem:_eventBtn snapToPoint:target];
    [_animator addBehavior:snapBehavior3];

這樣，所有三個按鈕會同時彈出。 我想問的是，是否可以使用UIDynamicAnimator使按鈕一個接一個地動畫，或者其他簡單的方法？

Answer 1

顯然我只需要添加一個很小的延遲，例如[[NSRunLoop currentRunLoop] runUntilDate:[NSDate dateWithTimeIntervalSinceNow:0.1]]; 之間addBehavior: