iOS / Swift - 向下/向上滚动时隐藏/显示UITabBarController

问题描述：

我对iOS开发很新。现在我正在尝试隐藏我的标签栏，当我向下滚动时，向上滚动标签栏应该出现。我想像导航栏一样动画这个动画。对于导航栏，我只需单击属性检查器中的选项。我看到了工具栏的一些示例，但我不能将其用作标签栏。

I'm quite new to iOS development. Right now i'm trying to hide my tabbar when I scroll down and when scrolling up the tabbar should appear. I would like to have this animated in the same way like the navigation bar. For the navigation bar I simply clicked the option in the Attributes Inspector. I saw some examples for the toolbar, but I cant adopt it the tabbar.

self.tabBarController？.tabBar.hidden = true 只是隐藏我的tabbar，但它不像导航控制器那样动画。

self.tabBarController?.tabBar.hidden = true just hides my tabbar, but its not animated like the navigation controller.

答

这是我实际在生产应用中使用的代码。

This is code that i'm actually using in a production app.

它在 Swift 中，它还会更新 UITabBar.hidden var。

It's in Swift and it also updates UITabBar.hidden var.

func scrollViewWillBeginDragging(scrollView: UIScrollView) {
    if scrollView.panGestureRecognizer.translation(in: scrollView).y < 0{
        changeTabBar(hidden: true, animated: true)
    }
    else{
        changeTabBar(hidden: false, animated: true)
    }
}

您还可以使用其他回调方法：

You can also use the other callback method:

func scrollViewDidScroll(scrollView: UIScrollView) {
    ...
}

但是如果你选择这样，那么你必须处理多个实际隐藏tabBar的辅助方法的调用。

but if you choose so, then you must handle multiple calls to the helper method that actually hides the tabBar.

然后你需要添加这个方法来激活tabBar的隐藏/显示。

And then you need to add this method that animates the hide/show of the tabBar.

func changeTabBar(hidden:Bool, animated: Bool){
    var tabBar = self.tabBarController?.tabBar
    if tabBar!.hidden == hidden{ return }
    let frame = tabBar?.frame
    let offset = (hidden ? (frame?.size.height)! : -(frame?.size.height)!)
    let duration:NSTimeInterval = (animated ? 0.5 : 0.0)
    tabBar?.hidden = false
    if frame != nil
    {
        UIView.animateWithDuration(duration,
            animations: {tabBar!.frame = CGRectOffset(frame!, 0, offset)},
            completion: {
                println($0)
                if $0 {tabBar?.hidden = hidden}
        })
    }
}

更新Swift 4

func changeTabBar(hidden:Bool, animated: Bool){
    guard let tabBar = self.tabBarController?.tabBar else { return; }
    if tabBar.isHidden == hidden{ return }
    let frame = tabBar.frame
    let offset = hidden ? frame.size.height : -frame.size.height
    let duration:TimeInterval = (animated ? 0.5 : 0.0)
    tabBar.isHidden = false

    UIView.animate(withDuration: duration, animations: {
        tabBar.frame = frame.offsetBy(dx: 0, dy: offset)
    }, completion: { (true) in
        tabBar.isHidden = hidden
    })
}

iOS / Swift - 向下/向上滚动时隐藏/显示UITabBarController

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