交互PopGesture时如何处理UITabBarController的子视图（如Flipboard）

Posted 2023-03-22

【中文标题】交互PopGesture时如何处理UITabBarController的子视图（如Flipboard）

【英文标题】：How to handle subviews of UITabBarController when interactivePopGesture (like Flipboard)

【发布时间】：2015-01-09 20:27:41

【问题描述】：

我想要一个下划线来指示选择了哪个项目。每当点击该项目时，它就会滑动到任何其他项目。因此，我在自定义UITabBarController 中添加了一个子视图并设置了动画。然后我使用hidesBottomBarWhenPushed 在推送时隐藏标签栏。但是，下划线似乎没有与自定义 UITabBarController 结合使用。

如何处理子视图，使其即使在使用后退手势时也始终位于顶部？这个Flipboard应用捕获是我想做的。

编辑：

CustomTabBarController.m
- (void)viewDidLoad

    [super viewDidLoad];

    // create underline view
    CGRect tabBarFrame = self.tabBar.frame;
    CGFloat itemWidth = (CGFloat)CGRectGetWidth(tabBarFrame) / MIN(5, self.tabBar.items.count);
    CGFloat originX = (CGFloat)itemWidth * self.selectedIndex;
    CGRect underlineFrame = CGRectMake(originX, CGRectGetMaxY(tabBarFrame) - 3.0f, itemWidth, 3.0f);

    self.underlineView = [[UIView alloc] initWithFrame:underlineFrame];
    self.underlineView.backgroundColor = [UIColor redColor];
    [self.view addSubview:self.underlineView];


#pragma mark - UITabBarDelegate

- (void)tabBar:(UITabBar *)tabBar didSelectItem:(UITabBarItem *)item

    NSUInteger itemIndex = [tabBar.items indexOfObject:item];
    CGRect underlineFrame = self.underlineView.frame;
    CGFloat originX = (CGFloat)CGRectGetWidth(self.underlineView.frame) * itemIndex;

    // underline shifting animation
    [UIView animateWithDuration:0.25
                     animations:^
                         self.underlineView.frame = CGRectMake(originX, underlineFrame.origin.y, CGRectGetWidth(underlineFrame), CGRectGetHeight(underlineFrame));
                     ];


CustomTableViewController.m
- (void)prepareForSegue:(UIStoryboardSegue *)segue sender:(id)sender

    UIViewController *detailViewController = segue.destinationViewController;
    detailViewController.hidesBottomBarWhenPushed = YES;

hidesBottomBarWhenPushed 隐藏标签栏，但隐藏其子视图（下划线视图）。 如果我自己隐藏它并在viewWillAppear 中显示它，下划线视图看起来不像在标签栏顶部。

【问题讨论】：

您应该首先展示您的一些代码，以便我们提供帮助。从图片中我看不出为什么你的可能不工作

【参考方案1】：

我终于找到了解决方法。要覆盖 hidesBottomBarWhenPushed 方法，您可以为标签栏的子视图添加替代视图。

sourceViewController.m

- (BOOL)hidesBottomBarWhenPushed

    [super hidesBottomBarWhenPushed];

    CustomTabBarController *tabBarController = (CustomTabBarController *)self.tabBarController;

    if (tabBarController.underlineView.isHidden) 

        CGRect tabBarBounds = tabBarController.tabBar.bounds;
        CGFloat underlineHeight = CGRectGetHeight(tabBarController.underlineView.frame);
        CGFloat itemWidth = (CGFloat)CGRectGetWidth(tabBarBounds) / MIN(5, tabBarController.tabBar.items.count);
        CGFloat originX = (CGFloat)itemWidth * tabBarController.selectedIndex;

        UIView *alternativeView = [[UIView alloc] initWithFrame:CGRectMake(originX, 
                                                                CGRectGetMaxY(tabBarBounds) - underlineHeight,
                                                                itemWidth,
                                                                underlineHeight)];
        alternativeView.tag = tabBarController.underlineViewTag;
        alternativeView.backgroundColor = tabBarController.underlineView.backgroundColor;
        [tabBarController.tabBar addSubview:alternativeView];
    

    return NO;


- (void)viewDidAppear:(BOOL)animated

    [super viewDidAppear:animated];

    CustomTabBarController *tabBarController = (CustomTabBarController *)self.tabBarController;

    if (tabBarController.underlineView.isHidden) 
        tabBarController.underlineView.hidden = NO;

        NSInteger underlineViewTag = tabBarController.underlineViewTag;
        UIView *alternativeView = [tabBarController.tabBar viewWithTag:underlineViewTag];
        [alternativeView removeFromSuperview];
    

不要忘记interactivePopGesture 无法弹出视图控制器的情况，替代视图仍会添加到标签栏。因此，如果需要，请在目标视图控制器中将其删除。

destinationViewController.m

- (void)viewDidAppear:(BOOL)animated

    [super viewDidAppear:animated];

    CustomTabBarController *tabBarController = (CustomTabBarController *)self.tabBarController;
    NSInteger underlineViewTag = tabBarController.underlineViewTag;
    UIView *alternativeView = [tabBarController.tabBar viewWithTag:underlineViewTag];

    if (alternativeView) [alternativeView removeFromSuperview];