objective-c - 为什么 NSURLConnection 的 currentRequest 在重定向后不指示正确的 URL？

Question

根据我对 NSURLConnection 文档的阅读，currentRequest 方法应该反射(reflect)加载时可能发生的任何重定向:

As the connection performs the load, the request may change as a result of protocol canonicalization or due to following redirects. This method is be used to retrieve the current value.

但是，当我检查 connectionDidFinishLoading: 中的 currentRequest 时，它始终具有原始请求的 URL，即使检查响应数据显示重定向已成功完成。 (请参阅下面的人为示例)

我的问题是:为什么 currentRequest 不返回实际的当前请求？我做错了什么还是这是预期的行为？如果这是 预期的行为，那么currentRequest 应该有什么用？

@interface AppDelegate : UIResponder <UIApplicationDelegate, NSURLConnectionDataDelegate>
@property (strong, nonatomic) NSURLConnection *connection;
@end

@implementation AppDelegate

- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions
{
    NSURL *url = [[NSURL alloc] initWithString:@"http://jigsaw.w3.org/HTTP/300/301.html"];
    NSURLRequest *request = [[NSURLRequest alloc] initWithURL:url];
    self.connection = [[NSURLConnection alloc] initWithRequest:request delegate:self];

    return YES;
}

- (NSURLRequest *)connection:(NSURLConnection *)connection willSendRequest:(NSURLRequest *)request redirectResponse:(NSURLResponse *)response
{
    NSLog(@"willSendRequest // request: %@ // currentRequest: %@", request, [connection currentRequest]);
    return request;
}

- (void)connectionDidFinishLoading:(NSURLConnection *)connection
{
    NSLog(@"didFinishLoading // originalRequest: %@ // currentRequest: %@", [connection originalRequest], [connection currentRequest]);
}

@end

运行此示例会得到以下输出:

2012-12-18 15:18:44.949 ConnectionTest[12534:c07] willSendRequest // request: <NSURLRequest http://jigsaw.w3.org/HTTP/300/301.html> // currentRequest: <NSURLRequest http://jigsaw.w3.org/HTTP/300/301.html>
2012-12-18 15:18:44.954 ConnectionTest[12534:c07] willSendRequest // request: <NSURLRequest http://jigsaw.w3.org/HTTP/300/Overview.html> // currentRequest: <NSURLRequest http://jigsaw.w3.org/HTTP/300/301.html>
2012-12-18 15:18:44.955 ConnectionTest[12534:c07] didFinishLoading // originalRequest: <NSURLRequest http://jigsaw.w3.org/HTTP/300/301.html> // currentRequest: <NSURLRequest http://jigsaw.w3.org/HTTP/300/301.html>

我的预期是最后一次调用 currentRequest 会显示以 Overview.html 结尾的页面 URL，但它仍然显示 301.html.

Answer 1

我只是想把这归咎于 Apple 不得不混淆文档。我可以通过检查响应对象获取最终请求 URL，但对我来说，名为 currentRequest 的东西应该反射(reflect)重定向后发出的最后一个请求。