将NSJSONSerialization从Swift转换为Objc C

Question

I am trying to convert a swift code to Objective C , since swift handles error by itself, I am little confuse about converting here, this is swift code :

  func connectionDidFinishLoading(connection: NSURLConnection){
        DictonaryData = (try! NSJSONSerialization.JSONObjectWithData(main_data, options: NSJSONReadingOptions.MutableContainers)) as! NSDictionary
              main_data = NSMutableData()
        delegate!.connectionDidFinish(self.identifier)
    }
}

and here is Objective C code

- (void)connectionDidFinishLoading:(NSURLConnection *)connection {

    NSError *error = nil;

    dictonaryData = (NSDictionary*)[NSJSONSerialization JSONObjectWithData:main_data options:NSJSONReadingMutableContainers error:&error];

}

In swift code there is code main_data = NSMutableData() delegate!.connectionDidFinish(self.identifier) how can I convert this part to objective c ? I am not familiar with swift. Thanks for your help

Answer 1

main_data = [NSMutableData new];
[delegate connectionDidFinish:self.identifier];

also

delegate!.connectionDidFinish(self.identifier)

will crash if connectionDidFinish not implemented for delegate object (same with my objective-c code). To fix crash you need change the Swift implementation to

delegate?.connectionDidFinish(self.identifier)

and for objective-c:

if ([delegate respondsToSelector:@selector(connectionDidFinish:)]) {
    [delegate connectionDidFinish:self.identifier];
}