Resize a UITextField while typing (by using Autolayout)

Question

I have a UITableViewCell which has two UITextFields (without borders). The following constraints are used to set up the horizontal layout.

@\"|-10-[leftTextFi

Answer 1

For some reason, calling invalidateIntrinsicContentSize wasn't working for me either, but I also ran into issues with the other solutions due to the margins and editing controls.

This solution isn't always needed; if invalidateIntrinsicContentSize works, then all that needs to be done is to add a call to that when the text is changed, as in the other answers. If that isn't working, then here's a solution (adapted from here) I found which also works with a clear control:

class AutoResizingUITextField: UITextField {
    var lastTextBeforeEditing: String?

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

    required init?(coder aDecoder: NSCoder) {
        super.init(coder: aDecoder)
        setupTextChangeNotification()
    }                

    func setupTextChangeNotification() {
        NotificationCenter.default.addObserver(
            forName: Notification.Name.UITextFieldTextDidChange,
            object: self,
            queue: OperationQueue.main) { (notification) in                   
                self.invalidateIntrinsicContentSize()
        }
        NotificationCenter.default.addObserver(
            forName: Notification.Name.UITextFieldTextDidBeginEditing,
            object: self,
            queue: OperationQueue.main) { (notification) in
                self.lastTextBeforeEditing = self.text
        }
    }                

    override var intrinsicContentSize: CGSize {
        var size = super.intrinsicContentSize

        if isEditing, let text = text, let lastTextBeforeEditing = lastTextBeforeEditing {
            let string = text as NSString
            let stringSize = string.size(attributes: typingAttributes)
            let origSize = (lastTextBeforeEditing as NSString).size(attributes: typingAttributes)
            size.width = size.width + (stringSize.width - origSize.width)
        }

        return size
    }

    deinit {
        NotificationCenter.default.removeObserver(self)
    }
}

If invalidateIntrinsicContentSize is working by itself, this will end up double-counting the change so that needs to be checked first.