iOS - UIView setCenter 在 UIView animateWithDuration 中不起作用

Question

我遇到了一个让我发疯的问题，我想我没有足够的知识来找到这个问题的答案。

这里是一个完美运行的代码:

NSLog(@"%f, %f", imageList.center.x, imageList.center.y);
[imageList setCenter:CGPointMake(imageList.center.x, -imageList.center.y)];
NSLog(@"=> %f, %f", imageList.center.x, imageList.center.y);

给我以下输出:

2016-01-08 11:48:42.585 User[4047:600095] 160.000000, 284.000000
2016-01-08 11:48:42.585 User[4047:600095] => 160.000000, -284.000000

现在，如果我把这个 setCenter 放到 UIView animationWithDuration 中，就像这样

NSLog(@"%f, %f", imageList.center.x, imageList.center.y);
[UIView animateWithDuration:0.3 animations:^{
   [imageList setCenter:CGPointMake(imageList.center.x, -imageList.center.y)];  
} completion:^(BOOL finished) {*/
    NSLog(@"=> %f, %f", imageList.center.x, imageList.center.y);
}];

我得到这个输出:

2016-01-08 11:48:42.585 User[4047:600095] 160.000000, 284.000000
2016-01-08 11:48:42.585 User[4047:600095] => 160.000000, 284.000000

你们知道为什么吗？我检查了约束和自动布局，一切都很好。

Answer 1

试试这个:

objective-C

[UIView animateWithDuration:0.3 delay:0.0 options:(UIViewAnimationOptionCurveLinear | UIViewAnimationOptionAllowUserInteraction) animations:^{
    [imageList setCenter:CGPointMake(imageList.center.x, -imageList.center.y)];
} completion:nil];

swift 4

UIView.animate(withDuration: 0.3, delay: 0.0, options: .curveLinear, animations: {
    imageList.center = CGPoint(x: imageList.center.x, y: -imageList.center.y)
}, completion: nil)