objective-c post json

先看同步，默認服務器接受json數據，返回json數據 

//同步post
-(NSString *)postSyn:(NSString *)urlStr jsonData:(NSString *)jsonData{
    NSLog(@"post_begin");

    NSData* postData = [jsonData dataUsingEncoding:NSUTF8StringEncoding allowLossyConversion:YES];//數據轉碼;
    NSString *length = [NSString stringWithFormat:@"%d", [postData length]];

    NSMutableURLRequest* request = [[NSMutableURLRequest alloc]init];
    [request setURL:[NSURL URLWithString:urlStr]]; //設置地址
    [request setHTTPMethod:@"POST"]; //設置發送方式
    [request setTimeoutInterval: 20]; //設置連接超時
    [request setValue:length forHTTPHeaderField:@"Content-Length"]; //設置數據長度
    [request setValue:@"application/json" forHTTPHeaderField:@"Content-Type"]; //設置發送數據的格式
    [request setValue:@"application/json" forHTTPHeaderField:@"Accept"]; //設置預期接收數據的格式
    [request setHTTPBody:postData]; //設置編碼後的數據

    //發起連接，接受響應
    NSHTTPURLResponse* urlResponse = nil;
    NSError *error = [[NSError alloc] init] ;
    NSData *responseData = [NSURLConnection sendSynchronousRequest:request
                                                 returningResponse:&urlResponse
                                                             error:&error];
    NSString *responseString = [[NSString alloc] initWithData:responseData encoding:NSUTF8StringEncoding]; //返回數據，轉碼

    NSLog(responseString);
    NSLog(@"post_end");
    return responseString;
}

將下面的代碼加入到某個類中，然後調用httpPost方法就可以了，這個是異步的 

-(void)httpPost:(NSString*)strcontext URL:(NSString*)urlstr{
    strcontext = nil;
    NSLog(@"url--%@",urlstr);
    NSLog(@"param--%@",strcontext);
    assert(strcontext!=NULL);
    assert(urlstr!=NULL);
    NSData* postData = [strcontext dataUsingEncoding:NSUTF8StringEncoding allowLossyConversion:YES];//轉碼
    NSString* postLength = [NSString stringWithFormat:@"%d",[postData length]];
    NSMutableURLRequest* request = [[[NSMutableURLRequest alloc]init]autorelease];
    [request setURL:[NSURL URLWithString:urlstr]]; //設置地址
    [request setHTTPMethod:@"POST"]; //設置發送方式
    [request setTimeoutInterval: 20]; //設置連接超時
    [request setValue:postLength forHTTPHeaderField:@"Content-Length"]; //設置數據長度
    [request setValue:@"application/json" forHTTPHeaderField:@"Content-Type"]; //設置發送數據的格式
    [request setValue:@"application/json" forHTTPHeaderField:@"Accept"]; //設置預期接收數據的格式
    [request setHTTPBody:postData]; //設置編碼後的數據
    NSURLConnection*conn=[[NSURLConnection alloc]initWithRequest:request delegate:self];  //設置類代理,注意要是self哦
    if(conn)
    {
        NSLog(@"ConnectionSuccess");
        [UIApplication sharedApplication].networkActivityIndicatorVisible=YES;
        [conn retain];
    }
    else
    {
        NSLog(@"ConnectionFailed");
        //informtheuserthatthedownloadcouldnotbemade
    }
}

#pragma mark------------------以下爲相應的回調函數-------------------------------
//收到響應時,會觸發
-(void)connection:(NSURLConnection*)connection didReceiveResponse:(NSURLResponse*)response{
    //注意這裏將NSURLResponse對象轉換成NSHTTPURLResponse對象才能去
    NSHTTPURLResponse*httpResponse=(NSHTTPURLResponse*)response;
    if([response respondsToSelector:@selector(allHeaderFields)]){
        NSDictionary*dictionary=[httpResponse allHeaderFields];
        NSLog(@"didReceiveResponse1:%@",[dictionary description]);
        NSLog(@"didReceiveResponse2:%d",[response statusCode]);
    }
}
//鏈接錯誤
-(void)connection:(NSURLConnection*)connection didFailWithError:(NSError*)error{
    //[selfperformSelectorOnMainThread:@selector(httpConnectEnd)withObject:nil waitUntilDone:NO];
    NSLog(@"didFailWithError:%@",[error localizedDescription]);
}
//Calledwhenachunkofdatahasbeendownloaded.
//接收數據每收到一次數據,會調用一次
-(void)connection:(NSURLConnection*)connection didReceiveData:(NSData*)data{
    //Processthedownloadedchunkofdata.
    NSLog(@"didReceiveData_length:%d",[data length]);
    // NSLog(@"didReceiveData_data:%d",[data description]);
    [[self responseData] appendData:data];
    NSLog(@"didReceiveData_data%@",[[NSString alloc]initWithData:data encoding:NSUTF8StringEncoding]);
    //[selfperformSelectorOnMainThread:@selector(updateProgress)withObject:nil waitUntilDone:NO];
}
//接收結束
-(void)connectionDidFinishLoading:(NSURLConnection*)connection{
    NSLog(@"connectionDidFinishLoading：%@",connection);
    //NSLog(@"%lld",received_);
    //[selfperformSelectorOnMainThread:@selector(httpConnectEnd)withObject:nil waitUntilDone:NO];
    //Settheconditionwhichendstherunloop.




    NSString *responseString = [[NSString alloc] initWithData:[self responseData] encoding:NSUTF8StringEncoding];
    [responseData release];

    NSLog(@"responseString：%@",responseString);
}