我正在努力使用我的导航控制器的子视图,其位置和尺寸都受到导航栏的限制 . 当我隐藏导航栏时,子视图消失(预期的行为) . 但是,当我带回导航栏时,子视图不会跟随 .
此子视图只是一个进度视图(我根据某些任务的进度填充颜色的自定义UIView)位于导航栏的顶部 .
在我的UINavigationController子类的viewDidLoad中使用约束设置进度视图的位置:
- (void) viewDidLoad{
// The dimensions here are totally arbitrary since they are going to be defined automatically by the constraints
_progressView = [[CRProgressView alloc] initWithFrame:CGRectMake(0, 0, 100, 100)];
[self.view addSubview:_progressView];
UINavigationBar *navBar = [self navigationBar];
[self.view addConstraint: [NSLayoutConstraint constraintWithItem:_progressView
attribute:NSLayoutAttributeBottom
relatedBy:NSLayoutRelationEqual
toItem:navBar
attribute:NSLayoutAttributeBottom
multiplier:1
constant:0]];
[self.view addConstraint: [NSLayoutConstraint constraintWithItem:_progressView
attribute:NSLayoutAttributeLeft
relatedBy:NSLayoutRelationEqual
toItem:navBar
attribute:NSLayoutAttributeLeft
multiplier:1
constant:0]];
[self.view addConstraint: [NSLayoutConstraint constraintWithItem:_progressView
attribute:NSLayoutAttributeRight
relatedBy:NSLayoutRelationEqual
toItem:navBar
attribute:NSLayoutAttributeRight
multiplier:1
constant:0]];
[self.view addConstraint: [NSLayoutConstraint constraintWithItem:_progressView
attribute:NSLayoutAttributeHeight
relatedBy:NSLayoutRelationEqual
toItem:navBar
attribute:NSLayoutAttributeHeight
multiplier:0
constant:2]];
[_progressView setTranslatesAutoresizingMaskIntoConstraints:NO];
}
从这里一切看起来都很好,但在某些时候,在导航控制器中显示的collectionView中,我调用[self.navigationController setNavigationBarHidden:YES animated:YES]来清除屏幕,并在用户在集合视图中向下滚动时有额外的空间 .
如果用户向上滚动,我会向后显示导航栏,但此处显示的导航栏没有进度视图 .
这是用于在collectionView中显示和隐藏导航栏的代码,但我不认为问题来自此处 . 它正确隐藏并显示navigationBar:
- (void) scrollViewDidScroll:(UIScrollView *)scrollView{
if (scrollView.contentOffset.y >= 0 && scrollView.contentOffset.y <= scrollView.contentSize.height - self.view.frame.size.height) {
if (self.lastContentOffsetY > scrollView.contentOffset.y) {
//Show navigation bar
if (self.navigationController.navigationBarHidden) {
[self.navigationController setNavigationBarHidden:NO animated:YES];
}
}
else if (self.lastContentOffsetY < scrollView.contentOffset.y) {
if (!self.navigationController.navigationBarHidden) {
[self.navigationController setNavigationBarHidden:YES animated:YES];
}
}
self.lastContentOffsetY = scrollView.contentOffset.y;
}
}
我不明白为什么当我调用[self.navigationController setNavigationBarHidden:NO animated:YES]时,进度视图没有返回导航栏 .
任何帮助将不胜感激 . 提前致谢 .
1 回答
我不确定它是否100%适用于您的情况,但您可以尝试插入此覆盖方法: