Question

我正在构建一个信使应用程序。

我当前的键盘通知功能如下：

func handleKeyboardNotification(notification: NSNotification) {

        if let userInfo = notification.userInfo {
            let keyboardFrame = userInfo[UIKeyboardFrameEndUserInfoKey]?.CGRectValue()
            print(keyboardFrame)


            let isKeyboardShowing = notification.name == UIKeyboardWillShowNotification


            bottomConstraint?.constant = isKeyboardShowing ? -keyboardFrame!.height : 0



            UIView.animateWithDuration(0, delay: 0, options: UIViewAnimationOptions.CurveEaseOut, animations: {

                self.view.layoutIfNeeded()
                }, completion: { (completed) in

                    if isKeyboardShowing {
                        let indexPath = NSIndexPath(forItem: self.messages!.count - 1, inSection: 0)
                        self.collectionView?.scrollToItemAtIndexPath(indexPath, atScrollPosition: .Bottom, animated: true)
                    }

            })

    }
}

（ bottomConstraint.constant 引用消息输入文本字段，该字段位于屏幕底部或键盘框架顶部）

但是，我希望完成参数中的操作与键盘打开时同时发生，而不是在键盘打开后。目前，当我关闭键盘时，它似乎自动布局很好，而不是在我打开它时。

到目前为止，我尝试过很多方法但无济于事。有什么建议吗？

Answer 1

如果您希望在完成时写入的代码块与键盘下降同时发生，那么您不应该在完成块中写入它。您可以在使用duration函数调用animate之前使用dispatch_async，因此它可以同时工作：

   func handleKeyboardNotification(notification: NSNotification) {

            if let userInfo = notification.userInfo {
                let keyboardFrame = userInfo[UIKeyboardFrameEndUserInfoKey]?.CGRectValue()
                print(keyboardFrame)


                let isKeyboardShowing = notification.name == UIKeyboardWillShowNotification


                bottomConstraint?.constant = isKeyboardShowing ? -keyboardFrame!.height : 0

DispatchQueue.main.async {
    if isKeyboardShowing {
                    let indexPath = NSIndexPath(forItem: self.messages!.count - 1, inSection: 0)
                            self.collectionView?.scrollToItemAtIndexPath(indexPath, atScrollPosition: .Bottom, animated: true)
}


            UIView.animateWithDuration(0, delay: 0, options: UIViewAnimationOptions.CurveEaseOut, animations: {self.view.layoutIfNeeded()}, completion: nil})

    }
}

滚动UICollectionView以响应键盘通知

1 个答案: