ios - 如何在 swift 4 中调整 UIViewController 中的 viewDidLoad 方法？ Swift 4 中不推荐使用initialize()

Question

我想在 UIViewController 扩展中混合 viewDidLoad，但在 swift3 中覆盖了 initialize() 方法swift4 不支持并且正在工作。谁能给我解决这个问题吗？我在 swift3 中的代码如下。

    extension UIViewController {

    open override class func initialize() {

        guard self === UIViewController.self else { return }
        swizzling(self)
    }

    // MARK: - Method Swizzling

    func nsh_viewDidLoad() {
        self.nsh_viewDidLoad()

        self.navigationItem.backBarButtonItem = UIBarButtonItem(title: "", style: .plain, target: nil, action: nil)
    }
    }

并且有一个全局方法

private let swizzling: (UIViewController.Type) -> () = { viewController in

    let originalSelector = #selector(viewController.viewDidLoad)
    let swizzledSelector = #selector(viewController.nsh_viewDidLoad)

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

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

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

Answer 1

我在 AppDelegate 中添加了以下代码，而不是 swizzling

let barButtonItemAppearance = UIBarButtonItem.appearance()
        barButtonItemAppearance.setTitleTextAttributes([NSAttributedStringKey.foregroundColor: UIColor.clear], for: .normal)
        barButtonItemAppearance.setTitleTextAttributes([NSAttributedStringKey.foregroundColor: UIColor.clear], for: .highlighted)