如何旋转NSURLConnection类的初始化方法

Question

我想旋转 NSURLConnection 类的初始化初始化方法，我已经尝试过这段代码，但它似乎对我不起作用

extension NSURLConnection{
public override class func initialize() {
    struct Static {
        static var token: dispatch_once_t = 0
    }
    dispatch_once(&Static.token) {
        let originalSelector = Selector("init:delegate:startImmediately:")
        let swizzledSelector = Selector("my_init:delegate:startImmediately:")
        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)
        }
    }
}
// MARK: - Method Swizzling
func my_init(request: NSURLRequest, delegate: AnyObject?, startImmediately: Bool){
 print("Inside Swizzled Method")
}
}

这是我从视图控制器发起的请求

let testPoint: String = "www.google.com"
    guard let url = NSURL(string: testPoint) else {
        print("Error: cannot create URL")
        return
    }
    let urlRequest = NSURLRequest(URL: url)
    let conn = NSURLConnection(request: urlRequest, delegate: self, startImmediately: true)

Answer 1

extension NSURLConnection{
public override class func initialize() {
    struct Static {
        static var token: dispatch_once_t = 0
    }
    if self !== NSURLConnection.self {
        return
    }
    dispatch_once(&Static.token) {
        let originalSelector = Selector("initWithRequest:delegate:startImmediately:")
        let swizzledSelector = Selector("initWithTest:delegate:startImmediately:")
        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)
        }
    }
}
// MARK: - Method Swizzling
convenience init(test: NSURLRequest, delegate: AnyObject?, startImmediately: Bool){
    print("Inside Swizzled Method")
    self.init()
}
}

Answer 2

我认为有两件事必须解决：

如本回答所述，您应该在originalSelector中使用 Objective-C 方法签名：

`let originalSelector = Selector("initWithRequest:delegate:startImmediately:")`

您不会从该方法返回任何内容my_init。您应该返回与正在切换的方法相同的类型，在本例中为 NSURLConnection .

func my_init(request: NSURLRequest, delegate: AnyObject?, startImmediately: Bool) -> NSURLConnection? {
    print("Inside Swizzled Method")
    //call the original initializer
    return my_init( request, delegate: delegate, startImmediately: startImmediately)
}

您可以看到my_init是在重排方法中调用的。在运行时中，它将调用原始initWithRequest:delegate:startImmediately因为此时方法已经交换

。

最后但并非最不重要的一点是，NSURLConnection在iOS 9中已弃用。强烈建议改用NSURLSession，因为它更现代并且具有更多有用的功能。