Ios 滚动UICollectionView以响应键盘通知

我正在构建一个messenger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是指位于屏幕底部或键盘框架顶部的消息输入文本字段）

但是，我希望完成参数中的操作与键盘打开同时发生，而不是在键盘打开后发生。目前，当我关闭键盘时，它似乎自动布局良好，只是在我打开键盘时没有

到目前为止，我已经尝试了很多方法，但都没有效果。

---

有什么建议吗？

如果您希望在键盘按下的同时完成编写的代码块，则不应在完成块中编写。 您可以在调用带持续时间的动画函数之前使用dispatch_async，这样它就可以同时工作：

   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})

    }
}

---

如果您希望在键盘按下的同时完成编写的代码块，则不应在完成块中编写。 您可以在调用带持续时间的动画函数之前使用dispatch_async，这样它就可以同时工作：

   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})

    }
}

---

我需要ScrollView在我的键盘出现时也移动，所以我使用了上面答案的一个版本：*DispatchQueue.main.async{self.scrollToBottomAnimated（动画：true）}**我需要ScrollView在我的键盘出现时也移动，因此，我使用了上述答案的一个版本：*DispatchQueue.main.async{self.scrollToBottomAnimated（动画：true）}**