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錯誤示例：

    //1.創建一個網絡路徑
    NSURL *url = [NSURL URLWithString:urlString];
    // 2.創建一個網絡請求
    NSURLRequest *request =[NSURLRequest requestWithURL:url];
    // 3.獲得會話對象
    NSURLSession *session = [NSURLSession sharedSession];
    // 4.根據會話對象，創建一個Task任務
 NSURLSessionDataTask *sessionDataTask = [session dataTaskWithRequest:request completionHandler:^(NSData * _Nullable data, NSURLResponse * _Nullable response, NSError * _Nullable error) {
        NSHTTPURLResponse *httpResponse = (NSHTTPURLResponse*)response;
        NSLog(@"從服務器獲取到數據 %ld",(long)httpResponse.statusCode);
        /*對從服務器獲取到的數據data進行相應的處理：*/
        NSDictionary *dict = [NSJSONSerialization JSONObjectWithData:data options:(NSJSONReadingMutableLeaves) error:nil];
        NSLog(@"%@",dict);
    }];
    // 5.最后一步，執行任務（resume也是繼續執行）:
    [sessionDataTask resume];```
>正確示例

 ``` Nsstring*urlString=@"https://graph.facebook.com/debug_token?input_token=/*facebook return token*/&access_token=/*apptoken*/";```
  ###urlString=[urlString stringByAddingPercentEncodingWithAllowedCharacters:[NSCharacterSet URLQueryAllowedCharacterSet]];###
  ``` NSURL *url = [NSURL URLWithString:urlString];;```