ios - animateWithDuration 不能淡入淡出

Question

我想在我的标签上先淡出然后淡入，我可以让两者分开工作但不能一起工作。

    [UILabel animateWithDuration:1.0 animations:^{
        _swixValla.alpha = 0.0;
        _skigoValla.alpha = 0.0;
        _rodeValla.alpha = 0.0;
        _startValla.alpha = 0.0;
    }];


    [UILabel animateWithDuration:1.0 animations:^{
        _swixValla.alpha = 1.0;
        _skigoValla.alpha = 1.0;
        _rodeValla.alpha = 1.0;
        _startValla.alpha = 1.0;
    }];

这行不通

    [UILabel animateWithDuration:1.0 animations:^{
        _swixValla.alpha = 0.0;
        _skigoValla.alpha = 0.0;
        _rodeValla.alpha = 0.0;
        _startValla.alpha = 0.0;


    [UILabel animateWithDuration:1.0 animations:^{
        _swixValla.alpha = 1.0;
        _skigoValla.alpha = 1.0;
        _rodeValla.alpha = 1.0;
        _startValla.alpha = 1.0;
    }];
    }];

这也不行。

我该如何解决这个问题？

Answer 1

如果你想在第一个完成后将它们组合起来开始第二个，请使用:

[UIView animateWithDuration:1.0 animations:^{
    _swixValla.alpha = 0.0;
    _skigoValla.alpha = 0.0;
    _rodeValla.alpha = 0.0;
    _startValla.alpha = 0.0;
}completion:^(BOOL finished){
    [UILabel animateWithDuration:1.0 animations:^{
        _swixValla.alpha = 1.0;
        _skigoValla.alpha = 1.0;
        _rodeValla.alpha = 1.0;
        _startValla.alpha = 1.0;
    }];
}];