How do I scroll the UIScrollView when the keyboard

Question

I'm having trouble with my code. I'm trying to move the UIScrollView when I'm editing an UITextField that should be hidden by the keyboard pop.

I'm moving the main frame right now because I don't know how to 'scroll up' in the code. So, I did a little bit of code, it's working fine but when I edit an UItextfield and I switch to another UITextField without pressing on the 'return' button the main view goes waaayyyyy to far up.

I did an NSLog() with my variables size, distance and textFieldRect.origin.y as you can see below. When I put two UITextField at the same place (y origin) and I do this particular 'switch' (wihtout pressing return) , I get the same numbers, whereas my code worked fine for the first UITextField editing but not for the second editing.

Check this out:

- (void)textFieldDidBeginEditing:(UITextField *)textField {
{
    int size;
    CGRect textFieldRect = [self.view.window convertRect:textField.bounds fromView:textField];
    size = textFieldRect.origin.y + textFieldRect.size.height;
    if (change == FALSE)
    {
        size = size - distance;
    }
    if (size < PORTRAIT_KEYBOARD_HEIGHT)
    {
        distance = 0;
    }
    else if (size > PORTRAIT_KEYBOARD_HEIGHT)
    {
        distance = size - PORTRAIT_KEYBOARD_HEIGHT + 5; // +5 px for more visibility
    }
    NSLog(@"origin %f", textFieldRect.origin.y);
    NSLog(@"size %d", size);
    NSLog(@"distance %d", distance);
    CGRect viewFrame = self.view.frame;
    viewFrame.origin.y -= distance;
    [UIView beginAnimations:nil context:NULL];
    [UIView setAnimationBeginsFromCurrentState:YES];
    [UIView setAnimationDuration:KEYBOARD_ANIMATION_DURATION];
    [self.view setFrame:viewFrame];
    [UIView commitAnimations];
    change = FALSE;
}

- (void)textFieldDidEndEditing:(UITextField *)textField
{
    change = TRUE;
    CGRect viewFrame = self.view.frame;
    viewFrame.origin.y += distance;
    [UIView beginAnimations:nil context:NULL];
    [UIView setAnimationBeginsFromCurrentState:YES];
    [UIView setAnimationDuration:KEYBOARD_ANIMATION_DURATION];
    [self.view setFrame:viewFrame];
    [UIView commitAnimations];
}

Any ideas ?

Answer 1

The recommended way from Apple is to change the contentInset of the UIScrollView. It is a very elegant solution, because you do not have to mess with the contentSize. Following code is copied from the Keyboard Programming Guide, where the handling of this issue is explained. You should have a look into it.

// Call this method somewhere in your view controller setup code.
- (void)registerForKeyboardNotifications
{
    [[NSNotificationCenter defaultCenter] addObserver:self
            selector:@selector(keyboardWasShown:)
            name:UIKeyboardDidShowNotification object:nil];
   [[NSNotificationCenter defaultCenter] addObserver:self
             selector:@selector(keyboardWillBeHidden:)
             name:UIKeyboardWillHideNotification object:nil];
}

// Called when the UIKeyboardDidShowNotification is sent.
- (void)keyboardWasShown:(NSNotification*)aNotification
{
    NSDictionary* info = [aNotification userInfo];
    CGSize kbSize = [[info objectForKey:UIKeyboardFrameBeginUserInfoKey] CGRectValue].size;
    UIEdgeInsets contentInsets = UIEdgeInsetsMake(0.0, 0.0, kbSize.height, 0.0);
    scrollView.contentInset = contentInsets;
    scrollView.scrollIndicatorInsets = contentInsets;

    // If active text field is hidden by keyboard, scroll it so it's visible
    // Your application might not need or want this behavior.
    CGRect aRect = self.view.frame;
    aRect.size.height -= kbSize.height;
    if (!CGRectContainsPoint(aRect, activeField.frame.origin) ) {
        CGPoint scrollPoint = CGPointMake(0.0, activeField.frame.origin.y-kbSize.height);
        [scrollView setContentOffset:scrollPoint animated:YES];
    }
}

// Called when the UIKeyboardWillHideNotification is sent    
- (void)keyboardWillBeHidden:(NSNotification*)aNotification
{
    UIEdgeInsets contentInsets = UIEdgeInsetsZero;
    scrollView.contentInset = contentInsets;
    scrollView.scrollIndicatorInsets = contentInsets;
}

Swift version:

func registerForKeyboardNotifications() {
    NotificationCenter.default.addObserver(self, selector: #selector(onKeyboardAppear(_:)), name: NSNotification.Name.UIKeyboardDidShow, object: nil)
    NotificationCenter.default.addObserver(self, selector: #selector(onKeyboardDisappear(_:)), name: NSNotification.Name.UIKeyboardDidHide, object: nil)
}

// Don't forget to unregister when done
deinit {
    NotificationCenter.default.removeObserver(self, name: NSNotification.Name.UIKeyboardDidShow, object: nil)
    NotificationCenter.default.removeObserver(self, name: NSNotification.Name.UIKeyboardDidHide, object: nil)
}

@objc func onKeyboardAppear(_ notification: NSNotification) {
    let info = notification.userInfo!
    let rect: CGRect = info[UIKeyboardFrameBeginUserInfoKey] as! CGRect
    let kbSize = rect.size

    let insets = UIEdgeInsetsMake(0, 0, kbSize.height, 0)
    scrollView.contentInset = insets
    scrollView.scrollIndicatorInsets = insets

    // If active text field is hidden by keyboard, scroll it so it's visible
    // Your application might not need or want this behavior.
    var aRect = self.view.frame;
    aRect.size.height -= kbSize.height;

    let activeField: UITextField? = [addressTextView, servicePathTextView, usernameTextView, passwordTextView].first { $0.isFirstResponder }
    if let activeField = activeField {
        if aRect.contains(activeField.frame.origin) {
            let scrollPoint = CGPoint(x: 0, y: activeField.frame.origin.y-kbSize.height)
            scrollView.setContentOffset(scrollPoint, animated: true)
        }
    }
}

@objc func onKeyboardDisappear(_ notification: NSNotification) {
    scrollView.contentInset = UIEdgeInsets.zero
    scrollView.scrollIndicatorInsets = UIEdgeInsets.zero
}

Answer 2

My solution has 4 step:
- Step 1: the function listens when the keyboard appears

- (void)keyboardWasShown:(NSNotification *)notification {
// Get the size of the keyboard.
CGSize keyboardSize = [[[notification userInfo] objectForKey:UIKeyboardFrameBeginUserInfoKey] CGRectValue].size;
//top: 64 for navigation bar, 0 for without navigation
UIEdgeInsets contentInsets = UIEdgeInsetsMake(64, 0, keyboardSize.height, 0);
_scrollView.contentInset = contentInsets;
_scrollView.scrollIndicatorInsets = contentInsets;
}

- Step 2: the function listens when the keyboard disappears

- (void)keyboardWillHide:(NSNotification *)notification {
//top: 64 for navigatiob bar
UIEdgeInsets contentInsets = UIEdgeInsetsMake(64, 0, 0, 0);
[_editScrollView setContentInset: contentInsets];
[_editScrollView setScrollIndicatorInsets: contentInsets];
}

- Step 3: add these functions to the notification center:

- (void)viewWillAppear:(BOOL)animated{
[super viewWillAppear:animated];
[[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(keyboardWasShown:) name:UIKeyboardDidShowNotification object:nil];
[[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(keyboardWillHide:) name:UIKeyboardWillHideNotification object:nil];
}

- Step 4: remove listen when view controller disappers

- (void)viewDidDisappear:(BOOL)animated{
[super viewDidDisappear:animated];
[[NSNotificationCenter defaultCenter]removeObserver:self name:UIKeyboardDidShowNotification object:nil];
[[NSNotificationCenter defaultCenter]removeObserver:self name:UIKeyboardWillHideNotification object:nil];
}

Answer 3

You can scroll by using the property contentOffset in UIScrollView, e.g.,

CGPoint offset = scrollview.contentOffset;
offset.y -= KEYBOARD_HEIGHT + 5;
scrollview.contentOffset = offset;

There's also a method to do animated scrolling.

As for the reason why your second edit is not scrolling correctly, it could be because you seem to assume that a new keyboard will appear every time editing starts. You could try checking if you've already adjusted for the "keyboard" visible position (and likewise check for keyboard visibility at the moment before reverting it).

A better solution might be to listen for the keyboard notification, e.g.:

[[NSNotificationCenter defaultCenter] addObserver:self
                                         selector:@selector(keyboardDidShow:)
                                             name:UIKeyboardDidShowNotification
                                           object:nil];
[[NSNotificationCenter defaultCenter] addObserver:self
                                         selector:@selector(keyboardWillHide:)
                                             name:UIKeyboardWillHideNotification
                                           object:nil];

Answer 4

The only thing I would update in Apple code is the keyboardWillBeHidden: method, to provide smooth transition.

// Called when the UIKeyboardWillHideNotification is sent
- (void)keyboardWillBeHidden:(NSNotification*)aNotification
{
    UIEdgeInsets contentInsets = UIEdgeInsetsZero;

    [UIView animateWithDuration:0.4 animations:^{
        self.scrollView.contentInset = contentInsets;
    }];
    self.scrollView.scrollIndicatorInsets = contentInsets;

}

Answer 5

Swift 4 Solution:

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

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

override func viewWillDisappear(_ animated: Bool) {
    super.viewWillDisappear(animated)
    NotificationCenter.default.removeObserver(self)
}

@objc func keyboardWillShow(notification: NSNotification) {
    let userInfo: NSDictionary = notification.userInfo! as NSDictionary
    let keyboardInfo = userInfo[UIKeyboardFrameBeginUserInfoKey] as! NSValue
    let keyboardSize = keyboardInfo.cgRectValue.size
    let contentInsets = UIEdgeInsets(top: 0, left: 0, bottom: keyboardSize.height, right: 0)
    scrollView.contentInset = contentInsets
    scrollView.scrollIndicatorInsets = contentInsets
}

@objc func keyboardWillHide(notification: NSNotification) {
    scrollView.contentInset = .zero
    scrollView.scrollIndicatorInsets = .zero
}

Answer 6

I used this answer supplied by Sudheer Palchuri https://stackoverflow.com/users/2873919/sudheer-palchuri https://stackoverflow.com/a/32583809/6193496

In ViewDidLoad, register the notifications:

NSNotificationCenter.defaultCenter().addObserver(self, selector: #selector(DetailsViewController.keyboardWillShow(_:)), name:UIKeyboardWillShowNotification, object: nil)
NSNotificationCenter.defaultCenter().addObserver(self, selector: #selector(DetailsViewController.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
self.scrollView.contentInset = contentInset
}

func keyboardWillHide(notification:NSNotification){

var contentInset:UIEdgeInsets = UIEdgeInsetsZero
self.scrollView.contentInset = contentInset
}