Question

我看起来像一个漂亮的香草关键帧动画：

NSTimeInterval duration = 5.;
[UIView animateKeyframesWithDuration:duration delay:0 options:0 animations:^{
    CGFloat intervals = 25.;
    for ( NSUInteger i = 0; i < intervals; i++) {
        CGFloat start = 1./intervals*i;
        CGFloat last = 1./intervals;
        NSLog(@"adding @ %f for %f", start, last);
        [UIView addKeyframeWithRelativeStartTime:start relativeDuration:last animations:^{
            CGFloat width = 12./intervals*(i+1);
            NSLog(@"setting to %f", width);
            self.colorWheel.lineWidth = width;
        }];
    }
} completion:^(BOOL finished) {
}];

不幸的是，我得到了这个输出：

2014-02-01 22:43:18.653 [26175:60b] adding @ 0.000000 for 0.040000
2014-02-01 22:43:18.655 [26175:60b] setting to 0.480000
2014-02-01 22:43:18.657 [26175:60b] adding @ 0.040000 for 0.040000
2014-02-01 22:43:18.658 [26175:60b] setting to 0.960000
2014-02-01 22:43:18.660 [26175:60b] adding @ 0.080000 for 0.040000
2014-02-01 22:43:18.661 [26175:60b] setting to 1.440000
2014-02-01 22:43:18.663 [26175:60b] adding @ 0.120000 for 0.040000
2014-02-01 22:43:18.665 [26175:60b] setting to 1.920000
2014-02-01 22:43:18.667 [26175:60b] adding @ 0.160000 for 0.040000
2014-02-01 22:43:18.668 [26175:60b] setting to 2.400000
2014-02-01 22:43:18.669 [26175:60b] adding @ 0.200000 for 0.040000
2014-02-01 22:43:18.671 [26175:60b] setting to 2.880000
...
2014-02-01 22:43:18.725 [26175:60b] adding @ 0.800000 for 0.040000
2014-02-01 22:43:18.727 [26175:60b] setting to 10.080000
2014-02-01 22:43:18.728 [26175:60b] adding @ 0.840000 for 0.040000
2014-02-01 22:43:18.728 [26175:60b] setting to 10.560000
2014-02-01 22:43:18.729 [26175:60b] adding @ 0.880000 for 0.040000
2014-02-01 22:43:18.730 [26175:60b] setting to 11.040000
2014-02-01 22:43:18.731 [26175:60b] adding @ 0.920000 for 0.040000
2014-02-01 22:43:18.732 [26175:60b] setting to 11.520000
2014-02-01 22:43:18.733 [26175:60b] adding @ 0.960000 for 0.040000
2014-02-01 22:43:18.734 [26175:60b] setting to 12.000000

您可以从输出中看到动画（“设置”）在添加动画（“添加”）后立即发生。似乎所有这些都应该被添加，然后所有这些都被执行，而不是以这种方式插入。

此外，duration值 5s ，但一切都在一秒钟内完成。为什么被忽略？

我的理论是，因为属于“动画”的属性实际上并不生成隐式动画（它是视图上的属性，而不是图层，而不是标准属性），动画基本上被拒绝了系统立即继续前进。

假设是这种情况，我怎么能a）告诉系统我想要它做的是在我的视图上调用drawRect:，这样它就可以在给定的时间呈现具有给定值的视图，或者b）告诉系统这个属性可以设置动画，然后尝试渲染我的视图吗？

或者，还有其他事情发生了吗？

UIView animateKeyframesWithDuration：立即执行所有帧

0 个答案: