◎위챗 : speedseoul
https://stackoverflow.com/questions/34281531/ios-9-best-solution-for-parsing-json
[[session dataTaskWithURL:request completionHandler:^(NSData *data, NSURLResponse *response, NSError *error) {
// handle response
NSError *parseError;
NSDictionary *json = [NSJSONSerialization JSONObjectWithData:data options:0 error:&parseError];
// do something with `json`
dispatch_async(dispatch_get_main_queue()), ^{[collectionView reloadData]});
}] resume];