Post请求

-(void)startPostRequest:(NSString *)url body:(NSString *)body flag:(BOOL)flag

{

    if (httpConnection) {

        [httpConnection release];

    }

    //如果url中包含中文,需要对它进行编码，在外部和这个方法内部编都可以

    NSURL *newURL=[NSURL URLWithString:[url stringByAddingPercentEscapesUsingEncoding:NSUTF8StringEncoding]];

    //创建请求对象

    NSMutableURLRequest *request=[NSMutableURLRequest requestWithURL:newURL];

    //设置请求方式为post

    [request setHTTPMethod:@"POST"];

    if (flag) {

        [request setValue:@"multipart/form-data" forHTTPHeaderField:@"Content-Type"];

    }

    else{

        [request addValue:@"application/x-www-form-urlencoded" forHTTPHeaderField:@"Content-Type"];

    }

    //设置请求体

    NSData *data=[body dataUsingEncoding:NSUTF8StringEncoding];

    [request setHTTPBody:data];

    [request setValue:[NSString stringWithFormat:@"%d",[data length]] forHTTPHeaderField:@"Content-Length"];

    httpConnection=[[NSURLConnection alloc] initWithRequest:request delegate:self];

}