I am trying to build an input screen for the iPhone. The screen has a number of input fields. Most of them on the top of the screen, but two fields are at the bottom. When the user tries to edit the text on the bottom of the screen, the keyboard will pop up and it will cover the screen. I found a simple solution to move the screen up when this happens, but the result is that the screen always moves up and the fields on top of the screen move out of reach when the user tries to edit those.
Is there a way to have the screen only move when the bottom fields are edited?
I have used this code I found here:
override func viewDidLoad() {
super.viewDidLoad()
NSNotificationCenter.defaultCenter().addObserver(self, selector: Selector("keyboardWillShow:"), name: UIKeyboardWillShowNotification, object: nil)
NSNotificationCenter.defaultCenter().addObserver(self, selector: Selector("keyboardWillHide:"), name: UIKeyboardWillHideNotification, object: nil)
}
func keyboardWillShow(sender: NSNotification) {
self.view.frame.origin.y -= 150
}
func keyboardWillHide(sender: NSNotification) {
self.view.frame.origin.y += 150
}
Your problem is well explained in this document by Apple. Example code on this page (at Listing 4-1) does exactly what you need, it will scroll your view only when the current editing should be under the keyboard. You only need to put your needed controls in a scrollViiew.
The only problem is that this is Objective-C and I think you need it in Swift..so..here it is:
Declare a variable
var activeField: UITextField?
then add these methods
func registerForKeyboardNotifications()
{
//Adding notifies on keyboard appearing
NSNotificationCenter.defaultCenter().addObserver(self, selector: "keyboardWasShown:", name: UIKeyboardWillShowNotification, object: nil)
NSNotificationCenter.defaultCenter().addObserver(self, selector: "keyboardWillBeHidden:", name: UIKeyboardWillHideNotification, object: nil)
}
func deregisterFromKeyboardNotifications()
{
//Removing notifies on keyboard appearing
NSNotificationCenter.defaultCenter().removeObserver(self, name: UIKeyboardWillShowNotification, object: nil)
NSNotificationCenter.defaultCenter().removeObserver(self, name: UIKeyboardWillHideNotification, object: nil)
}
func keyboardWasShown(notification: NSNotification)
{
//Need to calculate keyboard exact size due to Apple suggestions
self.scrollView.scrollEnabled = true
var info : NSDictionary = notification.userInfo!
var keyboardSize = (info[UIKeyboardFrameBeginUserInfoKey] as? NSValue)?.CGRectValue().size
var contentInsets : UIEdgeInsets = UIEdgeInsetsMake(0.0, 0.0, keyboardSize!.height, 0.0)
self.scrollView.contentInset = contentInsets
self.scrollView.scrollIndicatorInsets = contentInsets
var aRect : CGRect = self.view.frame
aRect.size.height -= keyboardSize!.height
if let activeFieldPresent = activeField
{
if (!CGRectContainsPoint(aRect, activeField!.frame.origin))
{
self.scrollView.scrollRectToVisible(activeField!.frame, animated: true)
}
}
}
func keyboardWillBeHidden(notification: NSNotification)
{
//Once keyboard disappears, restore original positions
var info : NSDictionary = notification.userInfo!
var keyboardSize = (info[UIKeyboardFrameBeginUserInfoKey] as? NSValue)?.CGRectValue().size
var contentInsets : UIEdgeInsets = UIEdgeInsetsMake(0.0, 0.0, -keyboardSize!.height, 0.0)
self.scrollView.contentInset = contentInsets
self.scrollView.scrollIndicatorInsets = contentInsets
self.view.endEditing(true)
self.scrollView.scrollEnabled = false
}
func textFieldDidBeginEditing(textField: UITextField!)
{
activeField = textField
}
func textFieldDidEndEditing(textField: UITextField!)
{
activeField = nil
}
Be sure to declare your ViewController as UITextFieldDelegate and set correct delegates in your initialization methods:
ex:
self.you_text_field.delegate = self
And remember to call registerForKeyboardNotifications on viewInit and deregisterFromKeyboardNotifications on exit.
func registerForKeyboardNotifications(){
//Adding notifies on keyboard appearing
NotificationCenter.default.addObserver(self, selector: #selector(keyboardWasShown(notification:)), name: NSNotification.Name.UIResponder.keyboardWillShowNotification, object: nil)
NotificationCenter.default.addObserver(self, selector: #selector(keyboardWillBeHidden(notification:)), name: NSNotification.Name.UIResponder.keyboardWillHideNotification, object: nil)
}
func deregisterFromKeyboardNotifications(){
//Removing notifies on keyboard appearing
NotificationCenter.default.removeObserver(self, name: NSNotification.Name.UIResponder.keyboardWillShowNotification, object: nil)
NotificationCenter.default.removeObserver(self, name: NSNotification.Name.UIResponder.keyboardWillHideNotification, object: nil)
}
@objc func keyboardWasShown(notification: NSNotification){
//Need to calculate keyboard exact size due to Apple suggestions
self.scrollView.isScrollEnabled = true
var info = notification.userInfo!
let keyboardSize = (info[UIResponder.keyboardFrameBeginUserInfoKey] as? NSValue)?.cgRectValue.size
let contentInsets : UIEdgeInsets = UIEdgeInsets(top: 0.0, left: 0.0, bottom: keyboardSize!.height, right: 0.0)
self.scrollView.contentInset = contentInsets
self.scrollView.scrollIndicatorInsets = contentInsets
var aRect : CGRect = self.view.frame
aRect.size.height -= keyboardSize!.height
if let activeField = self.activeField {
if (!aRect.contains(activeField.frame.origin)){
self.scrollView.scrollRectToVisible(activeField.frame, animated: true)
}
}
}
@objc func keyboardWillBeHidden(notification: NSNotification){
//Once keyboard disappears, restore original positions
var info = notification.userInfo!
let keyboardSize = (info[UIResponder.keyboardFrameBeginUserInfoKey] as? NSValue)?.cgRectValue.size
let contentInsets : UIEdgeInsets = UIEdgeInsets(top: 0.0, left: 0.0, bottom: -keyboardSize!.height, right: 0.0)
self.scrollView.contentInset = contentInsets
self.scrollView.scrollIndicatorInsets = contentInsets
self.view.endEditing(true)
self.scrollView.isScrollEnabled = false
}
func textFieldDidBeginEditing(_ textField: UITextField){
activeField = textField
}
func textFieldDidEndEditing(_ textField: UITextField){
activeField = nil
}