Scrollview and keyboard Swift

问题:

I'm new here and im starting with Swift for iOS.

I started creating a simple app that does some operations. But I'm having some problems when the keyboard appears, hiding one of my textFields. I think it's a common problem and I did some research but I couldn't find anything that solved my problem. And I want to use a Scroll rather than animate the textField to make it visible.

Thanks!!!!! (sorry for english mistakes)

回答1:

In ViewDidLoad, register the notifications:

NSNotificationCenter.defaultCenter().addObserver(self, selector: #selector(keyboardWillShow), name:UIKeyboardWillShowNotification, object: nil)
NSNotificationCenter.defaultCenter().addObserver(self, selector: #selector(keyboardWillHide), name:UIKeyboardWillHideNotification, object: nil)

Add below observer methods which does the automatic scrolling when keyboard appears.

func textFieldShouldReturn(textField: UITextField) -> Bool {
    textField.resignFirstResponder()
    return true
}

func keyboardWillShow(notification:NSNotification){

    var userInfo = notification.userInfo!
    var keyboardFrame:CGRect = (userInfo[UIKeyboardFrameBeginUserInfoKey] as! NSValue).CGRectValue()
    keyboardFrame = self.view.convertRect(keyboardFrame, fromView: nil)

    var contentInset:UIEdgeInsets = self.scrollView.contentInset
    contentInset.bottom = keyboardFrame.size.height
    scrollView.contentInset = contentInset
}

func keyboardWillHide(notification:NSNotification){

    let contentInset:UIEdgeInsets = UIEdgeInsetsZero
    scrollView.contentInset = contentInset
}

EDIT: This post was updated to reflect best practices in Swift 2.2 for Objective C selectors.

回答2:

The top answer for swift 3:

NotificationCenter.default.addObserver(self, selector: #selector(keyboardWillShow), name:NSNotification.Name.UIKeyboardWillShow, object: nil)
NotificationCenter.default.addObserver(self, selector: #selector(keyboardWillHide), name:NSNotification.Name.UIKeyboardWillHide, object: nil)

And then:

func keyboardWillShow(notification:NSNotification){
    //give room at the bottom of the scroll view, so it doesn't cover up anything the user needs to tap
    var userInfo = notification.userInfo!
    var keyboardFrame:CGRect = (userInfo[UIKeyboardFrameBeginUserInfoKey] as! NSValue).cgRectValue
    keyboardFrame = self.view.convert(keyboardFrame, from: nil)

    var contentInset:UIEdgeInsets = self.theScrollView.contentInset
    contentInset.bottom = keyboardFrame.size.height
    theScrollView.contentInset = contentInset
}

func keyboardWillHide(notification:NSNotification){
    let contentInset:UIEdgeInsets = UIEdgeInsets.zero
    theScrollView.contentInset = contentInset
}

回答3:

Here is a complete solution in Swift 4, utilizing guard and concise code. Plus correct code in keyboardWillHide to only reset the bottom to 0.

@IBOutlet weak var scrollView: UIScrollView!

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

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

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

private func unregisterNotifications() {
    NotificationCenter.default.removeObserver(self, name: UIResponder.keyboardWillShowNotification, object: nil)
    NotificationCenter.default.removeObserver(self, name: UIResponder.keyboardWillHideNotification, object: nil)
}

@objc func keyboardWillShow(notification: NSNotification){
    guard let keyboardFrame = notification.userInfo![UIResponder.keyboardFrameEndUserInfoKey] as? NSValue else { return }
    scrollView.contentInset.bottom = view.convert(keyboardFrame.cgRectValue, from: nil).size.height
}

@objc func keyboardWillHide(notification: NSNotification){
    scrollView.contentInset.bottom = 0
}

回答4:

contentInset doesn't work for me, because I want the scrollview move all the way up above the keyboard. So I use contentOffset:

func keyboardWillShow(notification:NSNotification) {
    guard let keyboardFrameValue = notification.userInfo?[UIKeyboardFrameBeginUserInfoKey] as? NSValue else {
        return
    }
    let keyboardFrame = view.convert(keyboardFrameValue.cgRectValue, from: nil)
    scrollView.contentOffset = CGPoint(x:0, y:keyboardFrame.size.height)
}

func keyboardWillHide(notification:NSNotification) {
    scrollView.contentOffset = .zero
}

回答5:

for Swift 4.0

In ViewDidLoad

// setup keyboard event
NotificationCenter.default.addObserver(self, selector: #selector(self.keyboardWillShow), name:UIResponder.keyboardWillShowNotification, object: nil)
NotificationCenter.default.addObserver(self, selector: #selector(self.keyboardWillHide), name:UIResponder.keyboardWillHideNotification, object: nil)

Add below observer methods which does the automatic scrolling when keyboard appears.

@objc func keyboardWillShow(notification:NSNotification){
    var userInfo = notification.userInfo!
    var keyboardFrame:CGRect = (userInfo[UIKeyboardFrameBeginUserInfoKey] as! NSValue).cgRectValue
    keyboardFrame = self.view.convert(keyboardFrame, from: nil)

    var contentInset:UIEdgeInsets = self.ui_scrollView.contentInset
    contentInset.bottom = keyboardFrame.size.height
    ui_scrollView.contentInset = contentInset
}

@objc func keyboardWillHide(notification:NSNotification){

    let contentInset:UIEdgeInsets = UIEdgeInsets.zero
    ui_scrollView.contentInset = contentInset
}

回答6:

Reading the links you sent to me, I found a way to make it work, thanks!:

func textFieldDidBeginEditing(textField: UITextField) {            
    if (textField == //your_field) {
        scrollView.setContentOffset(CGPointMake(0, field_extra.center.y-280), animated: true)
        callAnimation()
        viewDidLayoutSubviews()
    }
}

func textFieldDidEndEditing(textField: UITextField) {    
    if (textField == //your_field){
        scrollView .setContentOffset(CGPointMake(0, 0), animated: true)
        viewDidLayoutSubviews()
    }
}

回答7:

You can animate your scrollview to center on your UITextField on keyboard appearance (ie. making your textfield the first responder) via a scroll offset. Here are a couple of good resources to get you started (there are a bunch on this site):

How programmatically move a UIScrollView to focus in a control above keyboard?

How to make a UIScrollView auto scroll when a UITextField becomes a first responder

Additionally, if you simply use a UITableView with your content in cells, when the textfield becomes first responder, the UITableViewController will automatically scroll to the textfield cell for you (though I'm not sure this is what you want to do).

回答8:

From the answer by Sudheer Palchuri, converted for Swift 4.

In ViewDidLoad, register the notifications:

NotificationCenter.default.addObserver(self, selector: #selector(keyboardWillShow), name:NSNotification.Name.UIKeyboardWillShow, object: nil)
NotificationCenter.default.addObserver(self, selector: #selector(keyboardWillHide), name:NSNotification.Name.UIKeyboardWillHide, object: nil)

And then:

// MARK: - Keyboard Delegates
func textFieldShouldReturn(textField: UITextField) -> Bool {
    textField.resignFirstResponder()
    return true
}

@objc func keyboardWillShow(notification:NSNotification){

    var userInfo = notification.userInfo!
    var keyboardFrame:CGRect = (userInfo[UIKeyboardFrameBeginUserInfoKey] as! NSValue).cgRectValue
    keyboardFrame = self.view.convert(keyboardFrame, from: nil)

    var contentInset:UIEdgeInsets = self.scrollView.contentInset
    contentInset.bottom = keyboardFrame.size.height
    self.scrollView.contentInset = contentInset
}

@objc func keyboardWillHide(notification:NSNotification){

    let contentInset:UIEdgeInsets = UIEdgeInsets.zero
    self.scrollView.contentInset = contentInset
}

回答9:

An answer for Swift 3, based on the one proposed by Daniel Jones, but safer (thanks to the guard), more concise and with consistent scroll indicator insets:

@objc private func keyboardWillBeShown(notification: NSNotification) {
    guard let keyboardFrameValue = notification.userInfo?[UIKeyboardFrameBeginUserInfoKey] as? NSValue else { return }
    let keyboardFrame = view.convert(keyboardFrameValue.cgRectValue, from: nil)
    scrollView.contentInset.bottom = keyboardFrame.size.height
    scrollView.scrollIndicatorInsets = scrollView.contentInset
}

@objc private func keyboardWillBeHidden() {
    scrollView.contentInset = .zero
    scrollView.scrollIndicatorInsets = scrollView.contentInset
}

回答10:

override func viewDidLoad() {
    super.viewDidLoad()
    // Do any additional setup after loading the view, typically from a nib.

    NotificationCenter.default.addObserver(self, selector: #selector(ViewController.keyboardWillShow), name: NSNotification.Name.UIKeyboardWillShow, object: nil)

    NotificationCenter.default.addObserver(self, selector: #selector(ViewController.keyboardWillHide), name: NSNotification.Name.UIKeyboardWillHide, object: nil)

}

func keyboardWillShow(_ notification:Notification) {

    if let keyboardSize = (notification.userInfo?[UIKeyboardFrameBeginUserInfoKey] as? NSValue)?.cgRectValue {
        tableView.contentInset = UIEdgeInsetsMake(0, 0, keyboardSize.height, 0)
    }
}
func keyboardWillHide(_ notification:Notification) {

    if let keyboardSize = (notification.userInfo?[UIKeyboardFrameBeginUserInfoKey] as? NSValue)?.cgRectValue {
        tableView.contentInset = UIEdgeInsetsMake(0, 0, 0, 0)
    }
}

回答11:

In Swift4, just add the following extension.

extension UIViewController {

   func setupViewResizerOnKeyboardShown() {
        NotificationCenter.default.addObserver(self,
                                           selector: #selector(self.keyboardWillShowForResizing),
                                           name: 
        Notification.Name.UIKeyboardWillShow,
                                           object: nil)
        NotificationCenter.default.addObserver(self,
                                           selector: #selector(self.keyboardWillHideForResizing),
                                           name: Notification.Name.UIKeyboardWillHide,
                                           object: nil)
        }

   @objc func keyboardWillShowForResizing(notification: Notification) {
        if let keyboardSize = (notification.userInfo?[UIKeyboardFrameEndUserInfoKey] as? NSValue)?.cgRectValue,
        let window = self.view.window?.frame {
        // We're not just minusing the kb height from the view height because
        // the view could already have been resized for the keyboard before
        self.view.frame = CGRect(x: self.view.frame.origin.x,
                                 y: self.view.frame.origin.y,
                                 width: self.view.frame.width,
                                 height: window.origin.y + window.height - keyboardSize.height)
      } else {
        debugPrint("We're showing the keyboard and either the keyboard size or window is nil: panic widely.")
      }
  }

   @objc func keyboardWillHideForResizing(notification: Notification) {
     if let keyboardSize = (notification.userInfo?[UIKeyboardFrameEndUserInfoKey] as? NSValue)?.cgRectValue {
        let viewHeight = self.view.frame.height
        self.view.frame = CGRect(x: self.view.frame.origin.x,
                                 y: self.view.frame.origin.y,
                                 width: self.view.frame.width,
                                 height: viewHeight + keyboardSize.height)
    } else {
        debugPrint("We're about to hide the keyboard and the keyboard size is nil. Now is the rapture.")
    }
   }
 }

回答12:

In case anyone is looking for Objective-C code for this solution:

- (void)keyboardWasShown:(NSNotification *)notification {
        NSDictionary* info = [notification userInfo];
        CGSize kbSize = [[info objectForKey:UIKeyboardFrameBeginUserInfoKey] CGRectValue].size;
        UIEdgeInsets contentInsets = baseScrollView.contentInset;
        contentInsets.bottom = kbSize.height;
        baseScrollView.contentInset = contentInsets;
    }

    - (void)keyboardWillBeHidden:(NSNotification *)notification {
        UIEdgeInsets contentInsets = UIEdgeInsetsZero;
        baseScrollView.contentInset = contentInsets;
        [baseScrollView endEditing:YES];
    }