使用NSURLConnetion类的NSURLConnectionDataDelegate中的代理方法

- (nullable NSURLRequest *)connection:(NSURLConnection *)connection willSendRequest:(NSURLRequest *)request redirectResponse:(nullable NSURLResponse *)response

创建NSURLConnection对象发Request

    NSURL *url = [NSURL URLWithString:@"http://c.snnd.co/api/v4/click?campaign_id=4410534&publisher_id=52&rt=170401034908&_po=4f6801b69d272e96bbb920659a2f805b&_mw=p&_c=972&_cw=c&_ad=1288&publisher_slot=260&sub_1=pst2977485&pub_gaid=&pub_idfa=ADB6E76C-6B91-455B-81BE-DB884CC17818&pub_aid=&sub_2=695-669-773_33_0.300_20131822574410534260_iOS_1491019272&sub_3=Y29tLmdtZWRhbC5nb2xkZ21lZGFsKG5hdDMp_US_hcvr.ecpm5_i-1.5.3___ADB6E76C-6B91-455B-81BE-DB884CC17818&ch=pst"];
    NSMutableURLRequest *quest = [NSMutableURLRequest requestWithURL:url];
    quest.HTTPMethod = @"GET";
    NSURLConnection *connect = [NSURLConnection connectionWithRequest:quest delegate:self];
    [connect start];

- (nullable NSURLRequest *)connection:(NSURLConnection *)connection willSendRequest:(NSURLRequest *)request redirectResponse:(nullable NSURLResponse *)response{

    NSHTTPURLResponse *urlResponse = (NSHTTPURLResponse *)response;

    NSLog(@"%ld",urlResponse.statusCode);
    NSLog(@"%@",urlResponse.allHeaderFields);
    NSDictionary *dic = urlResponse.allHeaderFields;
    NSLog(@"%@",dic[@"Location"]);
    return request;
}

控制台输出如下：request 是你要发送的请求 urlResponse.statusCode 则是请求的状态码,302则是重定向 。

urlResponse.allHeaderFields中保存着http的头信息:
2017-04-01 14:14:13.923 URL302Demo[16338:587888] 302
2017-04-01 14:14:13.924 URL302Demo[16338:587888] {
    "Cache-Control" = "no-store, no-cache, must-revalidate, max-age=0";
    Connection = "keep-alive";
    "Content-Type" = "text/html; charset=UTF-8";
    Date = "Sat, 01 Apr 2017 06:14:13 GMT";
    Expires = "Thu, 01 Jan 1970 00:00:00 GMT";
    Location = "https://itunes.apple.com/us/app/star-wars-galaxy-of-heroes/id921022358";
    Pragma = "no-cache";
    Server = nginx;
    "Transfer-Encoding" = Identity;
}
2017-04-01 14:14:13.925 URL302Demo[16338:587888] https://itunes.apple.com/us/app/star-wars-galaxy-of-heroes/id921022358