iOS 拦截重定向302跳转的方法

<h1>一：前言</h1>
公司同事在做项目的时候遇到一个302地址跳转的问题，具体需求如下:
1、公司是做WIFI覆盖的，需要在下载APP后才能注册登录以后，自动连接到外网
2、苹果底层不允许我们码农进行WIFI的切换，所以公司考虑使用302重定向来实现，我通过2种方法来实现，NSURLConnetion和NSURLSession

二：NSURLConnetion方法
大概的思路:使用NSURLConnetion类的NSURLConnectionDataDelegate中的代理方法

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

都是码农，直接上代码吧
新建一个DEMO项目的话，记得把App Transport Security Settings Allow Arbitrary Loads设置为YES，否则无法请求网络

- (void)viewDidLoad {
    [super viewDidLoad];
  NSURL *url = [NSURL URLWithString:@"http://www.google.com"];
    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;
}

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:

{
    Connection = close;
    "Content-Type" = "text/html";
    Date = "Mon, 30 May 2016 04:00:49 GMT";
    Location = "http://118.244.233.137:6001/login/?gw_address=192.168.17.1&gw_port=2060&gw_id=ctzx_11&ip=192.168.17.24&mac=54:72:4f:30:c6:10&url=http%3A%2F%2Fwww.google.com%2F";
    Server = "Hughes Technologies Embedded Server";
}

通过urlResponse.allHeaderFields[@"Location"]即可拿到302跳转的url地址.如果需要拦截掉这个url地址跳转，则可在代理方法中自定义一个request

- (void)URLSession:(NSURLSession *)session task:(NSURLSessionTask *)task
willPerformHTTPRedirection:(NSHTTPURLResponse *)response
        newRequest:(NSURLRequest *)request
 completionHandler:(void (^)(NSURLRequest * __nullable))completionHandler{

   //block为nil，则直接拦截掉302的url地址，防止自动跳转
    completionHandler(nil);

}

则直接拦截掉302的url地址，防止自动跳转 completionHandler(nil);}

三：NSURLSession方法

- (void)viewDidLoad {
    [super viewDidLoad];
    NSURL *url = [NSURL URLWithString:@"http://www.google.com"];
    NSMutableURLRequest *quest = [NSMutableURLRequest requestWithURL:url];
    quest.HTTPMethod = @"GET";
    NSURLSessionConfiguration *config = [NSURLSessionConfiguration defaultSessionConfiguration];
    config.requestCachePolicy = NSURLRequestReloadIgnoringLocalCacheData;
    NSURLSession *urlSession = [NSURLSession sessionWithConfiguration:config delegate:self delegateQueue:[NSOperationQueue currentQueue]];
    
    NSURLSessionDataTask *task = [urlSession dataTaskWithRequest:quest completionHandler:^(NSData * _Nullable data, NSURLResponse * _Nullable response, NSError * _Nullable error) {
    
        NSHTTPURLResponse *urlResponse = (NSHTTPURLResponse *)response;
        
        NSLog(@"%ld",urlResponse.statusCode);
        NSLog(@"%@",urlResponse.allHeaderFields);
        
        NSDictionary *dic = urlResponse.allHeaderFields;
        NSLog(@"%@",dic[@"Location"]);
        
    }];
    
    [task resume];
    
}


- (void)URLSession:(NSURLSession *)session task:(NSURLSessionTask *)task
willPerformHTTPRedirection:(NSHTTPURLResponse *)response
        newRequest:(NSURLRequest *)request
 completionHandler:(void (^)(NSURLRequest * __nullable))completionHandler{

    completionHandler(nil);

}

使用方法和第一种方法一样
Demo下载​
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