Question

我有一个写入文件系统的异步保存方法。返回类型为void。我想在保存完成后立即更新ui。通常，我会使用then（）方法执行此操作，但不适用于void返回类型？那么保存完成后如何通知我？

  void save(Folder folder) async {  
   .....
  }

Answer 1

将返回类型更改为Future<void>。

Future<void> save(Folder folder) async {  
   .....
}

然后您可以执行await save(...);或save().then(...);

Answer 2

您可以使用extension UIView { func bindToKeyboard() { NotificationCenter.default.addObserver(self, selector: #selector(keyboardWillChange(_:)), name: UIResponder.keyboardWillChangeFrameNotification, object: nil) } @objc func keyboardWillChange(_ notification: NSNotification) { let duration = notification.userInfo![UIResponder.keyboardAnimationDurationUserInfoKey] as! Double let curve = notification.userInfo![UIResponder.keyboardAnimationCurveUserInfoKey] as! UInt let beginningFrame = (notification.userInfo![UIResponder.keyboardFrameBeginUserInfoKey] as! NSValue).cgRectValue let endFrame = (notification.userInfo![UIResponder.keyboardFrameEndUserInfoKey] as! NSValue).cgRectValue var deltaY = endFrame.origin.y - beginningFrame.origin.y UIView.animateKeyframes(withDuration: duration, delay: 0.0, options: UIView.KeyframeAnimationOptions(rawValue: curve), animations: { self.frame.origin.y += deltaY }, completion: nil) } }代替void。

Future<Null>

Flutter：等待异步void方法

2 个答案: