UIView方法快速3

Question

我正在尝试实现基于应答How to implement method swizzling swift 3.0?的swift 3中的方法

这是我的密码：

// 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()
        }
    }

}

但在应用程序启动时，它就有理由崩溃了：

'-UINavigationController swizzled_localization_awakeFromNib:未识别的选择器发送到实例0x7fc7c8820400‘

我不明白为什么swizzled_localization_awakeFromNib打电话给UINavigationController。我在obj-c项目中使用这个，这是原因吗？它在斯威夫特2通过dispatch_once很好地工作。

我在swizzling(self)，之前尝试了place断点，它在UIView上调用了一次，就像预期的那样。

Answer 1

问题是awakeFromNib是NSObject的一种方法，而不是UIView的方法。您的代码使用一个UIView方法对UIView方法进行处理，当UINavigationController (或者不是UIView子类的NSObject的任何其他子类)上调用swizzled方法时，调用原始方法就会崩溃。

解决方案是尝试添加带有原始名称的swizzled方法(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)
    }
}