ios - 将 NSJSONSerialization 从 Swift 转换为 Objc C

Question

我正在尝试将 swift 代码转换为 Objective C ，因为 swift 自己处理错误，所以我对这里的转换有点困惑，这是 swift 代码:

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

这是 Objective C 代码

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

    NSError *error = nil;

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

}

在 swift 代码中，有代码 main_data = NSMutableData() delegate!.connectionDidFinish(self.identifier)
如何将这部分转换为 Objective C ？我对 swift 不熟悉。感谢您的帮助

Answer 1

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

还有

delegate!.connectionDidFinish(self.identifier)

如果未为委托(delegate)对象实现 connectionDidFinish 将会崩溃(与我的 objective-c 代码相同)。要修复崩溃，您需要将 Swift 实现更改为

delegate?.connectionDidFinish(self.identifier)

对于 objective-c:

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