Changing the frame of an inputAccessoryView in iOS

问题:

Long time lurker - first time poster!

I am having an issue while recreating a bar with a UITextView like WhatsApp does it.

I am using a custom UIView subclass, and lazily instantiating it on:

- (UIView *)inputAccessoryView

and returning YES on:

- (BOOL)canBecomeFirstResponder

Now, I want to change the size of the inputAccessoryView when the UITextView grows in size. On iOS 7, I would simply change the size of the frame of said view - and not it's origin -, and then call reloadInputViews and it would work: the view would be moved upwards so that it is fully visible above the keyboard.

On iOS 8, however, this does not work. The only way to make it work is to also change the origin of the frame to a negative value. This would be fine, except it creates some weird bugs: for example, the UIView returns to the 'original' frame when entering any text.

Is there something I am missing? I am pretty certain WhatsApp uses inputAccessoryView because of the way they dismiss the keyboard on drag - only in the latest version of the app.

Please let me know if you can help me out! Or if there is any test you would like me to run!

Thank you! :)

BTW, here is the code I am using to update the height of the custom UIView called composeBar:

// ComposeBar frame size
CGRect frame = self.composeBar.frame;
frame.size.height += heightDifference;
frame.origin.y -= heightDifference;
self.composeBar.frame = frame;
[self.composeBar.textView reloadInputViews]; // Tried with this
[self reloadInputViews];                     // and this

Edit: full source code is available @ https://github.com/manuelmenzella/SocketChat-iOS

回答1:

I've been banging my head against the wall on this one for quite some time, as the behavior changed from iOS 7 to iOS 8. I tried everything, until the most obvious solution of all worked for me:

inputAccessoryView.autoresizingMask = UIViewAutoresizingFlexibleHeight;

duh!

回答2:

To sum up JohnnyC's answer: set your inpitAccessoryView's autoresizingMask to .flexibleHeight, calculate its intrinsicContentSize and let the framework do the rest.

Full code, updated for Swift 3:

class InputAccessoryView: UIView, UITextViewDelegate {

    let textView = UITextView()

    override var intrinsicContentSize: CGSize {
        // Calculate intrinsicContentSize that will fit all the text
        let textSize = textView.sizeThatFits(CGSize(width: textView.bounds.width, height: CGFloat.greatestFiniteMagnitude))
        return CGSize(width: bounds.width, height: textSize.height)
    }

    override init(frame: CGRect) {
        super.init(frame: frame)

        // This is required to make the view grow vertically
        autoresizingMask = .flexibleHeight

        // Setup textView as needed
        addSubview(textView)
        textView.translatesAutoresizingMaskIntoConstraints = false
        addConstraints(NSLayoutConstraint.constraints(withVisualFormat: "H:|[textView]|", options: [], metrics: nil, views: ["textView": textView]))
        addConstraints(NSLayoutConstraint.constraints(withVisualFormat: "V:|[textView]|", options: [], metrics: nil, views: ["textView": textView]))

        textView.delegate = self

        // Disabling textView scrolling prevents some undesired effects,
        // like incorrect contentOffset when adding new line,
        // and makes the textView behave similar to Apple's Messages app
        textView.isScrollEnabled = false
    }

    required init?(coder aDecoder: NSCoder) {
        fatalError("init(coder:) has not been implemented")
    }

    // MARK: UITextViewDelegate

    func textViewDidChange(_ textView: UITextView) {
        // Re-calculate intrinsicContentSize when text changes
        invalidateIntrinsicContentSize()
    }

}

回答3:

The issue is that in iOS 8, an NSLayoutConstraint that sets the inputAccessoryView's height equal to its initial frame height is installed automatically. In order to fix the layout problem, you need to update that constraint to the desired height and then instruct your inputAccessoryView to lay itself out.

- (void)changeInputAccessoryView:(UIView *)inputAccessoryView toHeight:(CGFloat)height {
    for (NSLayoutConstraint *constraint in [inputAccessoryView constraints]) {
        if (constraint.firstAttribute == NSLayoutAttributeHeight) {
            constraint.constant = height;
            [inputAccessoryView layoutIfNeeded];
            break;
        }
    }
}

回答4:

Here's a complete, self-contained solution (thanks @JohnnyC and @JoãoNunes for pointing me in the right direction, @stigi for explaining how to animate intrinsicContent changes):

class InputAccessoryView: UIView {

    // InputAccessoryView is instantiated from nib, but it's not a requirement
    override func awakeFromNib() {
        super.awakeFromNib()        
        autoresizingMask = .FlexibleHeight
    }

    override func intrinsicContentSize() -> CGSize {
        let exactHeight = // calculate exact height of your view here
        return CGSize(width: UIViewNoIntrinsicMetric, height: exactHeight)
    }

    func somethingDidHappen() {
        // invalidate intrinsic content size, animate superview layout        
        UIView.animateWithDuration(0.2) {
            self.invalidateIntrinsicContentSize()
            self.superview?.setNeedsLayout()
            self.superview?.layoutIfNeeded()
        }
    }
}

回答5:

100% working and very simple solution is to enumerate all constraints and set new height value. Here is some C# code (xamarin):

foreach (var constraint in inputAccessoryView.Constraints)
{
    if (constraint.FirstAttribute == NSLayoutAttribute.Height)
    {
        constraint.Constant = newHeight;
    }
}

回答6:

Unfortunately, iOS8 adds a private height constraint to the inputAccessoryView, and this constraint is not public.

I recommend recreating the accessory view when its frame should change, and call reloadInputViews so that the new one is installed.

This is what I do, and it works as expected.

回答7:

Yep, iOS8 adds a private height constraint to the inputAccessoryView.

Taking into account that recreating whole inputAccessoryView and replace old one is can be really expensive operation, you can just remove constraints before reload input views

[inputAccessoryView removeConstraints:[inputAccessoryView constraints]];
[textView reloadInputViews];

Just another workaround

回答8:

To fix this I used inputAccessoryView.autoresizingMask = UIViewAutoresizingFlexibleHeight;

But of course this caused my textview to collapse. So adding a constraint to the toolbar and updating it when I have to, or adding the constraint to the textview itself and update it worked for me.

回答9:

frist, get inputAccessoryView and set nil

UIView *inputAccessoryView = yourTextView.inputAccessoryView;
yourTextView.inputAccessoryView = nil;
[yourTextView reloadInputViews];

then set frame and layout

inputAccessoryView.frame = XXX
[inputAccessoryView setNeedsLayout];
[inputAccessoryView layoutIfNeeded];

last set new inputAccessoryView again and reload

yourTextView.inputAccessoryView = inputAccessoryView;
[yourTextView reloadInputViews];