xcode – NSURLConnection sendAsynchronousRequest：queue：com

我有一个REST API,它由摘要保护.我想下载我的 JSON响应,但首先我要对其余的api进行身份验证.
我正在使用sendAsynchronousRequest执行我的请求：queue：completionHandler：.但我不知道如何处理摘要身份验证.我想用委托方法didReceiveAuthenticationChallenge的NSURLConnectionDelegate这应该可行吗？我在.h文件中声明了NSURLConnectionDelegate,并在实现中添加了该方法.但没有任何反应.有关如何使用“sendAsynchronousRequest：queue：completionHandler：”处理此问题的任何建议？

NSURL *url = [NSURL URLWithString:@"http://restapi/"];

NSURLRequest *urlRequest = [NSURLRequest requestWithURL:url];
NSOperationQueue *queue = [[NSOperationQueue alloc] init];

[NSURLConnection sendAsynchronousRequest:urlRequest queue:queue completionHandler:^(NSURLResponse *response,NSData *data,NSError *error)
 {
     if ([data length] > 0 && error == nil)
         [self receivedData:data];
     else
         NSLog(@"error");
 }];

- (void)connection:(NSURLConnection *)connection didReceiveAuthenticationChallenge:(NSURLAuthenticationChallenge *)challenge {
NSLog(@"did get auth challenge"); }

NSURL *url = [NSURL URLWithString:@"http://restapi/"];

NSURLRequest *urlRequest = [NSURLRequest requestWithURL:url];
NSURLConnection *connection = [NSURLConnection connectionWithRequest:urlRequest delegate:self]