UIView 方法 swizzling swift 3

Question

我正在尝试根据答案 How to implement method swizzling swift 3.0? 在 swift 3 中实现方法调配

这是我的代码：

// MARK: - Swizzling

private let swizzling: (UIView.Type) -> () = { view in
    let originalSelector = #selector(view.awakeFromNib)
    let swizzledSelector = #selector(view.swizzled_localization_awakeFromNib)

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

    method_exchangeImplementations(originalMethod, swizzledMethod)
}

extension UIView {

    open override class func initialize() {
        guard self === UIView.self else {
            return
        }

        swizzling(self)
    }

    func swizzled_localization_awakeFromNib() {
        swizzled_localization_awakeFromNib()

        if let localizableView = self as? Localizable {
            localizableView.localize()
        }
    }

}

但在应用启动时它会因原因崩溃：

'-[UINavigationController swizzled_localization_awakeFromNib]: 无法识别的选择器发送到实例 0x7fc7c8820400'

我不明白为什么 swizzled_localization_awakeFromNib 调用 UINavigationController。我在 obj-c 项目中使用它，这可能是原因吗？它在 swift 2 throught dispatch_once 中运行良好。

我尝试在 swizzling(self) 之前放置断点，它在 UIView 上调用了一次，正如预期的那样。

Answer 1

问题是awakeFromNib 是NSObject 和 不是UIView。您的代码将 NSObject 方法与 UIView的方法，调用原方法崩溃 当在 UINavigationController 上调用 swizzled 方法时 （或NSObject 的任何其他子类，它不是UIView 的子类）。

解决方案是尝试添加 swizzled 方法 原名在前（如http://nshipster.com/method-swizzling/ 中所述）：

private let swizzling: (UIView.Type) -> () = { view in
    let originalSelector = #selector(view.awakeFromNib)
    let swizzledSelector = #selector(view.swizzled_localization_awakeFromNib)

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

    let didAddMethod = class_addMethod(view, originalSelector, method_getImplementation(swizzledMethod), method_getTypeEncoding(swizzledMethod))
    if didAddMethod {
        class_replaceMethod(view, swizzledSelector, method_getImplementation(originalMethod), method_getTypeEncoding(originalMethod))
    } else {
        method_exchangeImplementations(originalMethod, swizzledMethod)
    }
}