UIDynamicAnimator顺序动画

Question

我正在尝试使按钮从菜单按钮中弹出（类似于Path上的+按钮），并使用UIDynamicAnimator设置捕捉和退出按钮的动画。 它有效并且代码非常简单。

    _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];

这样，所有三个按钮会同时弹出。 我想问的是，是否可以使用UIDynamicAnimator使按钮一个接一个地动画，或者其他简单的方法？

Answer 1

显然我只需要添加一个很小的延迟，例如[[NSRunLoop currentRunLoop] runUntilDate:[NSDate dateWithTimeIntervalSinceNow:0.1]]; 之间addBehavior: