iOS使用NSURLConnection发送同步和异步HTTP Request

1. 同步发送

 

- (NSString *)sendRequestSync

{

    // 初始化请求, 这里是变长的, 方便扩展

    NSMutableURLRequest *request = [[NSMutableURLRequest alloc] init];

 

    // 设置

    [request setURL:[NSURL URLWithString:urlStr]];

    [request setHTTPMethod:@"POST"];

    [request setValue:host forHTTPHeaderField:@"Host"];

    NSString *contentLength = [NSString stringWithFormat:@"%d", [content length]];

    [request setValue:contentLength forHTTPHeaderField:@"Content-Length"];

    [request setHTTPBody:content];

 

    // 发送同步请求, data就是返回的数据

    NSError *error = nil;

    NSData *data = [NSURLConnection sendSynchronousRequest:request returningResponse:nilerror:&error];

    if (data == nil) {

        NSLog(@"send request failed: %@", error);

        return nil;

    }

 

    NSString *response = [[NSString alloc] initWithData:data encoding:NSUTF8StringEncoding];

    NSLog(@"response: %@", response);

    return response;

}

 

2.异步发送

 

1) 使用delegate的方式:

 

- (void)sendRequestAsync

{

   // 初始化请求

    NSMutableURLRequest  *request = [[NSMutableURLRequest alloc] init];

 

    // 设置

    [request setURL:[NSURL URLWithString:urlStr]];

    [request setCachePolicy:NSURLRequestUseProtocolCachePolicy]; // 设置缓存策略

    [request setTimeoutInterval:5.0]; // 设置超时

 

    //......

 

    receivedData = [[NSMutableData alloc] initData: nil];

    NSURLConnection *connection = [[NSURLConnection alloc] initWithRequest:request     delegate:self];

    if (connection == nil) {

        // 创建失败

        return;

    }

}

 

异步发送使用代理的方式, 需要实现以下delegate接口:

 

// 收到回应

- (void)connection:(NSURLConnection *)connection didReceiveResponse:(NSURLResponse *)response

{    

    NSLog(@"receive the response");

   // 注意这里将NSURLResponse对象转换成NSHTTPURLResponse对象才能去

   NSHTTPURLResponse *httpResponse = (NSHTTPURLResponse*)response;

   if ([response respondsToSelector:@selector(allHeaderFields)]) {

       NSDictionary *dictionary = [httpResponse allHeaderFields];

       NSLog(@"allHeaderFields: %@",dictionary);

   }

   [receivedData setLength:0];

}    

 

// 接收数据   

- (void)connection:(NSURLConnection *)connection didReceiveData:(NSData *)data    

{

    NSLog(@"get some data");

    [receivedData appendData:data];    

}

 

// 数据接收完毕

- (void)connectionDidFinishLoading:(NSURLConnection *)connection    

{

    NSString *results = [[NSString alloc]

                        initWithBytes:[receivedData bytes]

                        length:[receivedData length]

                        encoding:NSUTF8StringEncoding];

   NSLog(@"connectionDidFinishLoading: %@",results);

}

 

// 返回错误

-(void)connection:(NSURLConnection *)connection didFailWithError:(NSError *)error    

{   

    NSLog(@"Connection failed: %@", error);        

}    

2) iOS 5.0版本新增异步发送接口:

+ (void)sendAsynchronousRequest:(NSURLRequest *)request

                         queue:(NSOperationQueue*) queue

             completionHandler:(void (^)(NSURLResponse*, NSData*, NSError*)) handlerNS_AVAILABLE(10_7, 5_0);