从网络上进行数据的请求主要有SOAP方式和JSON方式，下面是我在看天气预报的例子时比较的两种方式的不同，在这里Mark一下。
SOAP方式：
使用SOAP获得天气预报支持的省直辖市信息
//封装soap请求消息
NSString*soapMessage = [NSStringstringWithFormat:
@"<?xml version=\"1.0\" encoding=\"utf-8\"?>\n"
"<soap:Envelope xmlns:xsi=\"http://www.w3.org/2001/XMLSchema-instance\" xmlns:xsd=\"http://www.w3.org/2001/XMLSchema\" xmlns:soap=\"http://schemas.xmlsoap.org/soap/envelope/\">\n"
"<soap:Body>\n"
"<getSupportProvince xmlns=\"http://WebXml.com.cn/\">\n"
"</getSupportProvince>\n"
"</soap:Body>\n"
"</soap:Envelope>\n",@"5"];
//请求发送到的路径
NSURL*url = [NSURLURLWithString:@"http://www.webxml.com.cn/WebServices/WeatherWebService.asmx"];
NSMutableURLRequest*theRequest = [NSMutableURLRequestrequestWithURL:url];
NSString*msgLength = [NSStringstringWithFormat:@"%d", [soapMessagelength]];
//以下对请求信息添加属性前四句是必有的，第五句是soap信息。
[theRequest addValue:@"text/xml; charset=utf-8"forHTTPHeaderField:@"Content-Type"];
[theRequest addValue:@"http://WebXml.com.cn/getSupportProvince"forHTTPHeaderField:@"SOAPAction"];
[theRequest addValue: msgLength forHTTPHeaderField:@"Content-Length"];
[theRequest setHTTPMethod:@"POST"];
[theRequest setHTTPBody: [soapMessagedataUsingEncoding:NSUTF8StringEncoding]];
//请求
NSURLConnection*theConnection = [[NSURLConnectionalloc]initWithRequest:theRequestdelegate:self];
//如果连接已经建好，则初始化data
if( theConnection )
{
webData= [[NSMutableDatadata]retain];
}
使用iOS自带解析类NSJSONSerialization方法解析（ios5以上版本支持）
//取得苏州的天气情况
NSError *error;
//加载一个NSURL对象
NSURLRequest*request = [NSURLRequestrequestWithURL:[NSURLURLWithString:@"http://m.weather.com.cn/data/101190401.html"]];
//将请求的数据放置到NSData中
NSData*reponse = [NSURLConnectionsendSynchronousRequest:requestreturningResponse:nilerror:nil];
//利用ios5自带的解析类NSJSONSerialization从response中解析出的数据放到字典中
NSDictionary*weatherDic = [NSJSONSerializationJSONObjectWithData:reponseoptions:NSJSONReadingMutableLeaveserror:&error];
NSDictionary *weather = [weatherDic objectForKey:@"weatherinfo"];
weatherStr = [NSString stringWithFormat:@"今天是%@,%@,%@\n天气状况是,%@,%@",[weather objectForKey:@"date_y"],[weather objectForKey:@"week"],[weather objectForKey:@"city"],[weather objectForKey:@"weather1"],[weather objectForKey:@"temp1"]];
NSLog(@"weather字典里的内容是:%@",weatherDic);