Question

我正在尝试为导航栏设置背景图片。

guard let navigationBar = navigationController?.navigationBar else { return }

let size = CGSize(width: navigationBar.bounds.width,
                  height: navigationBar.bounds.height + UIApplication.shared.statusBarFrame.height)
let image = #imageLiteral(resourceName: "NavigationBackground").resizedImage(newSize: size)
navigationBar.barTintColor = UIColor(patternImage: image)

func resizedImage(newSize: CGSize) -> UIImage {
    // Guard newSize is different
    guard self.size != newSize else { return self }

    UIGraphicsBeginImageContextWithOptions(newSize, false, 0.0)
    self.draw(in: CGRect(x: 0, y: 0, width: newSize.width, height: newSize.height))
    let newImage: UIImage = UIGraphicsGetImageFromCurrentImageContext()!
    UIGraphicsEndImageContext()
    return newImage
}

但是当我这样做时，显示导航栏的动画在模拟器和真实设备上变得非常慢。我做错了什么？

添加信息：看起来与事实相关的问题是在开始屏幕上我隐藏了viewWillAppear中的导航栏，然后在viewWillDisappear中再次显示它。如果我在第一个屏幕上显示导航，从屏幕到屏幕的导航没有问题

带有大标题栏的慢动画

0 个答案: