仅当文本字段隐藏时才使用键盘移动视图

Question

I'm trying to get my app to move the view when the keyboard appears, and so far the results have been... mixed to say the least. I can get it to move, thing is it's either hard coded or only works partially.

I have multiple Textfields in my view, when I tap on them, sometimes depending on where my scroll is it get's hidden by the keyboard.

Now what I need my app to do is to move the view to see the textfield only if the active textfield is hidden by the keyboard.

My Hierarchy for the view goes like this :

So I have a Scroll view, and in the scroll View I have a UIView named ContentView, in the ContentView I have all my textfields and labels.

thing is, I can't hard code it since My app is universal, I need to have the keyboard move the view only if it hides the textfield. Because in a situation where the user is on an iPad, the View will likely never have to move

I used the following Stack overflow answers with no results :

Swift: Scroll View only when a TextField or Button is hidden by the Keyboard

Move view with keyboard using Swift

here's my code that actually comes from one of those answers :

override func viewDidLoad() {
    super.viewDidLoad()

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

}



func keyboardWillShow(notification:NSNotification) {
    if keyboardIsPresent == false {
        if let keyboardSize = (notification.userInfo?[UIKeyboardFrameBeginUserInfoKey] as? NSValue)?.CGRectValue() {
            self.ContentView.frame.origin.y -= keyboardSize.height
            keyboardIsPresent = true
        }
    }
}

func keyboardWillHide(notification:NSNotification) {
    if keyboardIsPresent == true {
        if let keyboardSize = (notification.userInfo?[UIKeyboardFrameBeginUserInfoKey] as? NSValue)?.CGRectValue() {
            self.ContentView.frame.origin.y += keyboardSize.height
            keyboardIsPresent = false
        }
    }
}

I'm almost 100% sure all my error come from the fact the I have a ContentView... but I need it in my case. Thanks in advance for your help

Answer 1

Here is the code for it, It is pretty straight forward, but if you still need help with it, I will explain it further.

#pragma mark - Keyboard Observer events

-(void)keyboardWillShow:(NSNotification*)notification {

    NSDictionary *info = [notification userInfo];
    CGSize kbSize = [[info objectForKey:UIKeyboardFrameBeginUserInfoKey] CGRectValue].size;
    keyboardHeight = kbSize.height;
    [self updateScrollViewPosition];
}

-(void)keyboardDidChange:(NSNotification *)notification {

    NSDictionary *info = [notification userInfo];
    CGSize kbSizeBegin = [[info objectForKey:UIKeyboardFrameBeginUserInfoKey] CGRectValue].size;
    CGSize kbSizeEnd = [[info objectForKey:UIKeyboardFrameEndUserInfoKey] CGRectValue].size;
    if (kbSizeBegin.height != kbSizeEnd.height) {
        keyboardHeight = kbSizeEnd.height;
        if (activeTextField && [activeTextField isFirstResponder]) {
            [self updateScrollViewPosition];
        }
    }
}

-(void)keyboardWillHide:(NSNotification*)notification {

    keyboardHeight = 0;
    activeTextField = nil;
    [self resignAllTextFields];
}

#pragma mark - UITextFieldDelegate Methods

- (BOOL)textFieldShouldBeginEditing:(UITextField *)textField {
    activeTextField = textField;
    return YES;
}

- (void)textFieldDidBeginEditing:(UITextField *)textField {

    activeTextField = textField;
    [self updateScrollViewPosition];
}

- (BOOL)textFieldShouldReturn:(UITextField *)textField {

    keyboardHeight = 0;
    activeTextField = nil;
    [textField resignFirstResponder];
    return YES;
}

#pragma mark - Update Method

-(void)updateScrollViewPosition {

    if (keyboardHeight > 0 && activeTextField) {
        CGRect frame = activeTextField.frame;
        CGFloat yPoint = scrollView.frame.origin.y+frame.origin.y+frame.size.height+8.0;
        CGFloat height = self.view.frame.size.height-keyboardHeight;
        CGFloat diff = yPoint-height;
        if (diff > 0.0) {
            [scrollView setContentOffset:CGPointMake(0, diff) animated:YES];
        }
        else {
            CGFloat diff = scrollView.contentSize.height-scrollView.contentOffset.y;
            if (diff<scrollView.frame.size.height) {
                diff = scrollView.contentSize.height-scrollView.frame.size.height;
                if (diff < 0) {
                    diff = 0.0;
                }
                [scrollView setContentOffset:CGPointMake(0, diff) animated:YES];
            }
        }
    }
    else {
        CGFloat diff = scrollView.contentSize.height-scrollView.contentOffset.y;
        if (diff<scrollView.frame.size.height) {
            diff = scrollView.contentSize.height-scrollView.frame.size.height;
            if (diff < 0) {
                diff = 0.0;
            }
            [scrollView setContentOffset:CGPointMake(0, diff) animated:YES];
        }
    }
}

#pragma mark

Edit: A simple resignAllTextFields method as requested. containerView is the view which contains all the UITextField .

-(void)resignAllTextFields {

    for (UIView *view in containerView.subviews) {
        if ([view isKindOfClass:[UITextField class]]) {
            UITextField *textField = (UITextField*)view;
            [textField resignFirstResponder];
        }
    }
    [self updateScrollViewPosition];
}

Answer 2

You should not modify frames when keyboard shows up.

Instead you need to set the bottom inset of the scrollview scrollView.contentInset.bottom from zero to keyboard height. When the keyboard disappears, you set the inset back to zero.

This whole problem is solvable by mere 10 lines of code.

literally get the keyboard height from notification, store it ion a local variable in the class while KB is showing, and use the value to set insets in delegate callback/event handler methods.

The trick here is that setting nonzero insets will effectively scroll the scrollview together with the content for you up by and that will push the current textfield up as well.

Answer 3

You should first try to locate the UITextField instance by using the following code.

extension UIView {

    func firstResponder() -> UIView? {
        if self.isFirstResponder() {
            return self
        }

        for subview in self.subviews {
            if subview.isFirstResponder() {
                return subview
            }
        }

        return nil
    }

}

In the keyboardWillShow: function decide if the textfield is visible or not if the keyboard comes up.

func keyboardWillShow(notification:NSNotification) {
    if keyboardIsPresent == false {
        if let keyboardSize = (notification.userInfo?[UIKeyboardFrameBeginUserInfoKey] as? NSValue)?.CGRectValue(),
            let inputView = self.ContentView.firstResponder()
            where inputView.frame.maxY > self.ContentView.frame.size.height - keyboardSize.height {

            self.ContentView.frame.origin.y -= keyboardSize.height
            keyboardIsPresent = true

        }
    }
}

Than only move the view back in the hide function if it was moved away.