Swift 4.2 Make bottom of tableView move up when keyboard shows

问题

Although I've searched, I'm confused about how best to approach this.

I have a tableView where the bottom cell is an input to the list, in the same way apple reminders work. When there are too many items on the list, the keyboard covers the list and I can't see what I'm typing.

My thought it I need to change the physical size of the table view and ensure it is scrolled to the bottom when the keyboard shows.

Some have said keyboard observers but the majority of code I've found for this is out of date and errors when put into Xcode.

NSNotificationCenter Swift 3.0 on keyboard show and hide

This is the best I can find but I'm also hearing about contraints, using a UITableViewController instead of embedding a UITableView and so on ...

This is the code I have so far:

NotificationCenter.default.addObserver(self, selector: #selector(EntryViewController.keyboardWillShow), name: UIResponder.keyboardWillShowNotification, object: nil)
NotificationCenter.default.addObserver(self, selector: #selector(EntryViewController.keyboardWillHide), name: UIResponder.keyboardWillHideNotification, object: nil)


@objc func keyboardWillShow(notification: Notification) {
    if let keyboardSize = (notification.userInfo?[UIResponder.keyboardFrameEndUserInfoKey] as? NSValue)?.cgRectValue {
        print("notification: Keyboard will show")
        if self.view.frame.origin.y == 0{
            self.view.frame.origin.y -= keyboardSize.height
        }
    }

}

@objc func keyboardWillHide(notification: Notification) {
    if let keyboardSize = (notification.userInfo?[UIResponder.keyboardFrameEndUserInfoKey] as? NSValue)?.cgRectValue {
        if self.view.frame.origin.y != 0 {
            self.view.frame.origin.y += keyboardSize.height
        }
    }
}

This moves the whole view up I think, which means safeareas (such as navigation bar and so on) have the TableView underneath them. Do I make the navigationview non-transparent in this approach?

回答1:

One solution (which I sometimes use) is simply change the content offset of the tableView when the keyboard appears/disappears. I believe this would work in your instance as opposed to varying the tableView's constraints as you mentioned your UIViewController is a UITableViewController. Please see the below code for my suggestion, hope this helps!

Handle Notifications:

override func viewWillAppear(_ animated: Bool) {
    super.viewWillAppear(animated)

    NotificationCenter.default.addObserver(self, selector: #selector(EntryViewController.keyboardWillShow), name: UIResponder.keyboardWillShowNotification, object: nil)
    NotificationCenter.default.addObserver(self, selector: #selector(EntryViewController.keyboardWillHide), name: UIResponder.keyboardWillHideNotification, object: nil)
}

override func viewWillDisappear(_ animated: Bool) {
    super.viewWillDisappear(animated)

    NotificationCenter.default.removeObserver(self)
}

Actions:

@objc func keyboardWillShow(notification: Notification) {
    if let keyboardHeight = (notification.userInfo?[UIResponder.keyboardFrameEndUserInfoKey] as? NSValue)?.cgRectValue.height {
        print("Notification: Keyboard will show")
        tableView.setBottomInset(to: keyboardHeight)
    }
}

@objc func keyboardWillHide(notification: Notification) {
    print("Notification: Keyboard will hide")
    tableView.setBottomInset(to: 0.0)
}

Extensions:

extension UITableView {

    func setBottomInset(to value: CGFloat) {
        let edgeInset = UIEdgeInsets(top: 0, left: 0, bottom: value, right: 0)

        self.contentInset = edgeInset
        self.scrollIndicatorInsets = edgeInset
    }
}

来源：https://stackoverflow.com/questions/54455940/swift-4-2-make-bottom-of-tableview-move-up-when-keyboard-shows

标签

ios

swift

keyboard

tableview