当用户在 table 视图中向下滚动时，如何将 UINavigationBar 背景颜色从透明更改为红色

Question

我有一个 table 视图和它前面的导航栏。我希望当用户向下滚动时，导航栏的背景颜色开始从透明变为红色，就像增加 alpha 一样。

我的问题是，当用户向下滚动时，当导航栏背景 alpha 为 1.0 时，用户仍然可以看到导航栏后面！

这是我的代码：

override func viewDidLoad() {
    super.viewDidLoad()

    self.mainProfileTableView.contentInset = UIEdgeInsetsMake(-44,0,0,0);


    self.navigationController?.navigationBar.isOpaque = true
    UIApplication.shared.statusBarView?.backgroundColor = UIColor.init(red: 180/255, green: 40/255, blue: 56/255, alpha: 1.0)

    self.navigationController?.navigationBar.barTintColor = UIColor.init(red: 180/255, green: 40/255, blue: 56/255, alpha: 1.0)


    self.navigationController?.navigationBar.setBackgroundImage(UIImage(named : "navigationBarBackGround"), for: .default)

    self.navigationController?.navigationBar.shadowImage = UIImage()
    self.navigationController?.navigationBar.isTranslucent = true
    self.navigationController?.view.backgroundColor = UIColor.init(red: 180/255, green: 40/255, blue: 56/255, alpha: 1.0)

}

这是检测用户向上或向下滚动的方法

var lastContentOffset: CGFloat = 0


func scrollViewDidScroll(_ scrollView: UIScrollView) {
    if (self.lastContentOffset < scrollView.contentOffset.y) {
        // moved to top
        print("move Up\(scrollView.contentOffset.y)")
        print("alpha\(Float(scrollView.contentOffset.y / 166))")
        navigationController?.navigationBar.alpha = scrollView.contentOffset.y / 166

    } else if (self.lastContentOffset > scrollView.contentOffset.y) {
        // moved to bottom

        navigationController?.navigationBar.alpha = scrollView.contentOffset.y / 166
        print("alpha\(Float(scrollView.contentOffset.y / 166))")
        print("move down\(scrollView.contentOffset.y)")

    } else {

        // didn't move
    }
}

Answer 1

难道导航栏是半透明的？像这样：

使用以下方式更改它：

self.navigationController?.navigationBar.isTranslucent = False

并删除：

self.navigationController?.navigationBar.setBackgroundImage...
self.navigationController?.navigationBar.shadowImage = UIImage()

然后在用户滚动时修改barTintColor。

Answer 2

谢谢你的帮助但是我应该在滚动视图中使用半透明的 false Did Change Method 所以答案是这样

func scrollViewDidScroll(_ scrollView: UIScrollView) {
if (self.lastContentOffset < scrollView.contentOffset.y) {
    // moved to top
    print("move Up\(scrollView.contentOffset.y)")
    print("alpha\(Float(scrollView.contentOffset.y / 166))")
    navigationController?.navigationBar.alpha = scrollView.contentOffset.y / 166
    if Float(scrollView.contentOffset.y / 166) >= 1.0 {

            self.navigationController?.navigationBar.isTranslucent = false

            }

} else if (self.lastContentOffset > scrollView.contentOffset.y) {
    // moved to bottom

    navigationController?.navigationBar.alpha = scrollView.contentOffset.y / 166
    print("alpha\(Float(scrollView.contentOffset.y / 166))")
    print("move down\(scrollView.contentOffset.y)")

} else {

    // didn't move
}
}

当用户在 table 视图中向下滚动时，如何将 UINavigationBar 背景颜色从透明更改为红色

How to change UINavigationBar background color from clear to red when user scrolls down in the table view

uinavigationbar

uitableview

uiscrollview

ios

swift