iOS5:willSendRequestForAuthenticationChallenge方法正在运行递归

Question

我使用下面的代码来验证远程服务器的用户.如果我给出正确的用户名和密码,没有问题,因为身份验证正在发生,我从服务器获得响应.

但是当我提供错误的凭据时,会以递归方式调用此方法,因此我无法解决此问题.

请帮助我,如何打破这一点,以便我能够显示身份验证失败的警报消息.

- (void)connection:(NSURLConnection *)connection willSendRequestForAuthenticationChallenge:(NSURLAuthenticationChallenge *)challenge
{

    NSURLCredential *credential = [NSURLCredential credentialWithUser:@"username"
                                                             password:@"password"
                                                          persistence:NSURLCredentialPersistenceForSession];
    [[challenge sender] useCredential:credential forAuthenticationChallenge:challenge];    
}

Answer 1

您需要检查错误计数并相应地取消身份验证质询:

if ([challenge previousFailureCount]) {
    [[challenge sender] cancelAuthenticationChallenge:challenge];
} else {
    [[challenge sender] useCredential:credential forAuthenticationChallenge:challenge];
}