在 iOS 11 Swift 4 上应用渐变后,UINavigationBar 标题和按钮消失

UINavigationBar Title and Buttons disappear after gradient is applied on iOS 11 Swift 4

我最近升级到 Xcode 9,Swift 4 又更新了所有 iOS 模拟器。 自更新以来,我发现在对 UINavigationBar 应用渐变后;标题和按钮没有出现,但仍然有功能。

这是应用渐变的代码 -

extension UIView {

    func applyNavGradient(colours: [UIColor]) -> Void {
       self.applyNavGradient(colours: colours, locations: nil)
    }

    func applyNavGradient(colours: [UIColor], locations: [NSNumber]?) -> Void {
       let gradient: CAGradientLayer = CAGradientLayer()
       gradient.frame = self.bounds
       gradient.colors = colours.map { [=12=].cgColor }
       gradient.locations = locations
       self.layer.addSublayer(gradient)
       self.backgroundColor = UIColor.clear
    } 
}

class ViewController {

        override func viewDidLoad() {
            UINavigationBar.applyNavGradient(colours: redFade)
        }

这曾经在 Xcode 8 和 iOS10 -

中工作

现在我得到的只有这个;

谁能告诉我为什么会发生变化??

提前致谢!

克里斯

您可以使用UIColor.init(patternImage image: UIImage)方法分配barTintColor of navigationBar

这里是示例代码

func applyNavGradient(colours: [UIColor]) -> UIImage? {

    let gradientLayer: CAGradientLayer = CAGradientLayer()
    gradientLayer.frame = CGRect(x: 0, y: 0, width: UIScreen.main.bounds.size.width, height: navigationController!.navigationBar.frame.size.height + navigationController!.navigationBar.frame.origin.y)
    gradientLayer.colors = colours.map { [=10=].cgColor }
    gradientLayer.startPoint = CGPoint(x: 0.5, y: 0.0)
    gradientLayer.endPoint = CGPoint(x: 0.5, y: 1.0)

    UIGraphicsBeginImageContext(gradientLayer.bounds.size)
    gradientLayer.render(in: UIGraphicsGetCurrentContext()!)
    let image = UIGraphicsGetImageFromCurrentImageContext()
    UIGraphicsEndImageContext()
    return image

}

之后可以这样调用来设置渐变

if let img = applyNavGradient(colours: [UIColor.red, UIColor.yellow]) {
    navigationController?.navigationBar.barTintColor = UIColor(patternImage: img)
}