我想同时执行两个运动动画。 firstView
上的第一个动画立即开始。 secondView
上的第二个动画在第一个动画仍在运行时略有延迟后开始。 secondView
约束与firstView
相关。该代码在 iOS 8 上运行良好。
firstView
和 secondView
是 view
的 subview
view
|--- firstView
|--- secondView
代码:
UIView *firstView = ...;
UIView *secondView = ...;
[UIView animateWithDuration:0.5 delay:0 options:UIViewAnimationOptionCurveEaseInOut animations:^{
NSLayoutConstraint *constraint = [NSLayoutConstraint constraintWithItem:firstView attribute:NSLayoutAttributeTop relatedBy:NSLayoutRelationEqual toItem:self.topLayoutGuide attribute:NSLayoutAttributeBottom multiplier:1.0 constant:0];
[self.view addConstraint:constraint];
[self.view layoutIfNeeded];
} completion:^(BOOL finished) {
}];
[UIView animateWithDuration:0.5 delay:0.15 options:UIViewAnimationOptionCurveEaseInOut animations:^{
NSLayoutConstraint *constraint = [NSLayoutConstraint constraintWithItem:secondView attribute:NSLayoutAttributeTop relatedBy:NSLayoutRelationEqual toItem:firstView attribute:NSLayoutAttributeBottom multiplier:1.0 constant:0];
[self.view addConstraint:constraint];
[self.view layoutIfNeeded];
} completion:^(BOOL finished) {
}];
在 iOS 7 上,一旦第二个 layoutIfNeeded
被调用,第一个动画停止,只有第二个动画动画。
有什么建议吗?
最佳答案
回答我自己的问题。
我最终用两步(三步,取决于你如何计算)解决方案来制作动画。首先在不调用 layoutIfNeeded
的情况下添加约束。然后更新 firtView
和 secondView
框架。最后在最后一个动画的完成 block 中调用 layoutIfNeeded
。
代码:
UIView *firstView = ...;
UIView *secondView = ...;
/* first step */
NSLayoutConstraint *constraint1 = [NSLayoutConstraint constraintWithItem:firstView attribute:NSLayoutAttributeTop relatedBy:NSLayoutRelationEqual toItem:self.topLayoutGuide attribute:NSLayoutAttributeBottom multiplier:1.0 constant:0];
[self.view addConstraint:constraint1];
NSLayoutConstraint *constraint2 = [NSLayoutConstraint constraintWithItem:secondView attribute:NSLayoutAttributeTop relatedBy:NSLayoutRelationEqual toItem:firstView attribute:NSLayoutAttributeBottom multiplier:1.0 constant:0];
[self.view addConstraint:constraint2];
/* second step */
[UIView animateWithDuration:0.5 delay:0 options:UIViewAnimationOptionCurveEaseInOut animations:^{
CGRect firstViewFrame = CGRectMake(...); // set frame according to constaint1
firstView.frame = firstViewFrame;
}];
[UIView animateWithDuration:0.5 delay:0.15 options:UIViewAnimationOptionCurveEaseInOut animations:^{
CGRect secondViewFrame = CGRectMake(...); // set frame according to constaint2
secondView.frame = secondViewFrame;
} completion:^(BOOL finished) {
/* second and a half step */
[self.view setNeedsLayout];
[self.view layoutIfNeeded];
}];
关于iOS - 使用自动布局执行多个同步动画,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/28557452/