在重定向之前停止 NSURL 连接，同时获取重定向 URL

Question

我正在尝试取回 url 的响应正文，该响应正文重定向到另一个无效的 url。我也想停止重定向，因为它会使我的应用崩溃。

我曾尝试在我的代码中使用以下方法，但没有被采纳：

func URLSession(_ session: NSURLSession,
    dataTask dataTask: NSURLSessionDataTask,
    didReceiveResponse response: NSURLResponse,
    completionHandler completionHandler: (NSURLSessionResponseDisposition) -> Void) {
        print("Did you get here?")
}

func URLSession(_ session: NSURLSession,
    task task: NSURLSessionTask,
    didCompleteWithError error: NSError?) {
        print("How about here?")
}

func URLSession(_ session: NSURLSession,
    task task: NSURLSessionTask,
    willPerformHTTPRedirection response: NSHTTPURLResponse,
    newRequest request: NSURLRequest,
    completionHandler completionHandler: (NSURLRequest?) -> Void) {
        print("Maybe here?")
}

func URLSession(_ session: NSURLSession,
    didBecomeInvalidWithError error: NSError?) {
        print("Did you find an error?")
}

对我能做什么有什么想法吗？

编辑：所以，这是我拥有的更新代码，使用 XCode 7 时不会出现错误：

class Example: NSObject, NSURLSessionDelegate, NSURLSessionTaskDelegate {


override init() {
    super.init()

    let mySession = NSURLSession(configuration: NSURLSessionConfiguration.ephemeralSessionConfiguration(), delegate: self, delegateQueue: NSOperationQueue.mainQueue())

    // Put your handler as the second parameter.
    let data = try!mySession.dataTaskWithURL(NSURL(string: "http://www.google.com")!, completionHandler: myHandler)

    data!.resume()
}

// Create your handler with the following signature, and read the response body.
func myHandler(data: NSData?, response: NSURLResponse?, error: NSError?) -> Void {

    // In this case the “encoding” is NSASCIIStringEnconding. It depends on the website.
    let responseBody = NSString(data: data!, encoding: NSASCIIStringEncoding)

    print(responseBody)
}



// Handles redirection
private func URLSession(session: NSURLSession, task: NSURLSessionTask, willPerformHTTPRedirection response: NSHTTPURLResponse, newRequest request: NSURLRequest, completionHandler: (NSURLRequest!) -> Void) {

    // Stops the redirection, and returns (internally) the response body.
    completionHandler(nil)
}

}

Answer 1

要停止重定向并获取响应正文，您应该调用 completionHandler 并使用 nil 作为参数。

停止重定向后，当您使用dataTaskWithURL:completionHandler:（也可以是dataTaskWithRequest:completionHandler:）创建HTTP Get 请求时，URLSession 将调用您指定的处理程序。然后在处理程序中你得到响应体。示例：

import Foundation

class Example: NSObject, NSURLSessionDelegate, NSURLSessionTaskDelegate {


    override init() {
        super.init()

        let mySession = NSURLSession(configuration: NSURLSessionConfiguration.ephemeralSessionConfiguration(), delegate: self, delegateQueue: NSOperationQueue.mainQueue())

        // Put your handler as the second parameter.
        let data = mySession.dataTaskWithURL(NSURL(string: "http://www.google.com")!, completionHandler: myHandler)

        data.resume()
    }

    // Create your handler with the following signature, and read the response body.
    func myHandler(data: NSData!, response: NSURLResponse!, error: NSError!) -> Void {

        // In this case the “encoding” is NSASCIIStringEnconding. It depends on the website.
        let responseBody = NSString(data: data, encoding: NSASCIIStringEncoding)

        println(responseBody)
    }



    // Handles redirection
    func URLSession(session: NSURLSession, task: NSURLSessionTask, willPerformHTTPRedirection response: NSHTTPURLResponse, newRequest request: NSURLRequest, completionHandler: (NSURLRequest!) -> Void) {

        // Stops the redirection, and returns (internally) the response body.
        completionHandler(nil)
    }
}

苹果参考：https://developer.apple.com/library/ios/documentation/Foundation/Reference/NSURLSessionTaskDelegate_protocol/index.html#//apple_ref/occ/intfm/NSURLSessionTaskDelegate/URLSession:task:willPerformHTTPRedirection:newRequest:completionHandler：

我知道它适用于 HTTP 302 代码，但对于 301（永久移动）或 308 等其他代码，我不知道它是否有效。

值得补充（关于URLSession:task:willPerformHTTPRedirection:newRequest:completionHandler:）：

仅在默认和临时会话中的任务调用此方法。后台会话中的任务会自动遵循重定向。