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);