我需要在QImage的滚动条上更改UIView位置。当我在动画块中更改tableview的帧大小时，它会向下移动，然后移动到正确的位置。请看我的代码。
UIView - (void)scrollViewDidScroll:(UIScrollView *)scrollView {
CGPoint scrollVelocity = [_collectionViewLeaderboard.panGestureRecognizer velocityInView:_collectionViewLeaderboard.superview];
if (scrollVelocity.y > 0.0f){
NSLog(@"going down");
[UIView animateWithDuration:0.3f
animations:^ {
_headerview.frame = CGRectMake(0, 0, _headerview.frame.size.width, _headerview.frame.size.height);
_headerviewSecond.frame = CGRectMake(0, _headerview.frame.size.height, _headerviewSecond.frame.size.width, _headerviewSecond.frame.size.height);
self.collectionViewLeaderboard.frame = CGRectMake(self.view.frame.origin.x, _headerviewSecond.frame.size.height+_headerview.frame.size.height, self.view.frame.size.width, self.view.frame.size.height);
frameconditon = _headerview.frame;
} completion:^ (BOOL completed) {
}];
}
else if (scrollVelocity.y < 0.0f){
NSLog(@"going up");
//CGAffineTransform transform = CGAffineTransformMake(1, 0, 0, 1, _headerview.frame.origin.x, _headerview.frame.origin.y);
[UIView animateWithDuration:5.0 animations:^{
NSLog(@"test");
_headerview.frame = CGRectMake(0, -(_headerview.frame.size.height), _headerview.frame.size.width, _headerview.frame.size.height);
_headerviewSecond.frame = CGRectMake(0, (_headerview.frame.size.height)-40, _headerviewSecond.frame.size.width, _headerviewSecond.frame.size.height);
} completion:^(BOOL finished) {
}];
self.collectionViewLeaderboard.frame = CGRectMake(self.view.frame.origin.x, _headerviewSecond.frame.size.height, self.view.frame.size.width, self.view.frame.size.height);
}
}
应该移到视图顶部并且它可以工作但是当我第一次运行时，它会向下并返回到正确的位置。如何在滚动时更改约束。
答案 0 :(得分：1)
对于基于约束的视图，尝试使用插座通过更改约束常量属性设置动画。