Question

在我的app委托中，我调用以下代码将每个VC的导航栏颜色设置为蓝色。但是，如果用户没有登录并只是将应用程序旋转，我希望导航栏为红色。

UINavigationBar.appearance().barTintColor = UIColor(red: 108.0/255.0, green: 158.0/255.0, blue: 236.0/255.0, alpha: 1.0) // Blue

//    UINavigationBar.appearance().barTintColor = UIColor(red: 239.0/255.0, green: 119.0/255.0, blue: 97.0/255.0, alpha: 1.0) // Red

UINavigationBar.appearance().tintColor = .white
UINavigationBar.appearance().titleTextAttributes = [NSForegroundColorAttributeName : UIColor.white]

如何根据每个VC的用户选择更改颜色？

Answer 1

以viewWillAppear方式更改每个VC中的颜色

override func viewWillAppear(_ animated: Bool) {
    super.viewWillAppear(true)
    navigationController?.navigationBar.barTintColor = UIColor(red: 0/255.0, green: 210/255.0, blue: 255/255.0, alpha: 1.0)
 }

如果您正在等待某些事件发生，那么您可能会在完成后更改。像这样

navigationController?.navigationBar.barTintColor = UIColor(red: 0/255.0, green: 210/255.0, blue: 255/255.0, alpha: 1.0)

Answer 2

将UIViewController的以下扩展名添加到您的项目中，请注意这是“在所有视图控制器上运行相同代码”的最简单，最直接的方法，但它使用方法调配 。虽然我在下面编写的代码非常安全，如果您不知道自己在做什么，它可能会导致意外/意外行为。 谨慎行事。

extension UIViewController {
    public override class func initialize() {
        struct Static {
            static var token: dispatch_once_t = 0
        }

        // make sure this isn't a subclass
        if self !== UIViewController.self {
            return
        }

        dispatch_once(&Static.token) {
            let originalSelector = Selector("viewWillAppear:")
            let swizzledSelector = Selector("extended_viewWillAppear:")

            let originalMethod = class_getInstanceMethod(self, originalSelector)
            let swizzledMethod = class_getInstanceMethod(self, swizzledSelector)

            let didAddMethod = class_addMethod(self, originalSelector, method_getImplementation(swizzledMethod), method_getTypeEncoding(swizzledMethod))

            if didAddMethod {
                class_replaceMethod(self, swizzledSelector, method_getImplementation(originalMethod), method_getTypeEncoding(originalMethod))
            } else {
                method_exchangeImplementations(originalMethod, swizzledMethod)
            }
        }
    }

    func extended_viewWillAppear(animated: Bool) {
        self.extended_viewWillAppear(animated)

        // Call your code here that you want to run for all view controllers, table view controllers, tab view controllers etc...
        navigationController?.navigationBar.barTintColor = UIColor(red: 0/255.0, green: 210/255.0, blue: 255/255.0, alpha: 1.0)
    }
}

如何根据用户选择更改每个VC的导航栏控制器颜色？

2 个答案: