iOS9获取所在城市的接口及解析(简单的NSURLSession使用和新的编码方法使用)

[code]/* 定位当前城市的方法调用 */
[self asynGETJSONWithURL:@"http://int.dpool.sina.com.cn/iplookup/iplookup.php?format=js" completion:^(id result) {
        NSLog(@"%@", result[@"city"]);
    }];

[code]/* 方法实现 */
- (void)asynGETJSONWithURL:(NSString *)urlString completion:(void(^)(id result))block {
    /* 1.转码 */
    NSString *enCodingStr = [urlString stringByAddingPercentEncodingWithAllowedCharacters:[NSCharacterSet URLQueryAllowedCharacterSet]];
    /* 2.创建URL对象 */
    NSURL *url = [NSURL URLWithString:enCodingStr];
    /* 3.创建请求 */
    NSURLRequest *request = [NSURLRequest requestWithURL:url];
    /* 4.创建链接接受数据 */
    NSURLSessionTask *task = [[NSURLSession sharedSession] dataTaskWithRequest:request completionHandler:^(NSData *data, NSURLResponse *response, NSError *error) {

        /* 5.数据解析 */

        NSString *temResult = [[NSString alloc] initWithData:data  encoding:NSUTF8StringEncoding];
        if (temResult.length == 0) {
            return ;
        }
        temResult = [temResult substringFromIndex:21];
        temResult = [temResult substringToIndex:temResult.length - 1];
        NSData* xmlData = [temResult dataUsingEncoding:NSUTF8StringEncoding];
        id result = [NSJSONSerialization JSONObjectWithData:xmlData options:NSJSONReadingMutableContainers error:&error];
        /* 6.通过block将result值返回出去 */
        block(result);
    }];
    [task resume];
}