Expanding UITextView with UIButton instead of automatically based on content - ios

Question

I have a UITextView which is embedded in a UIView amongst a number of other UIViews which are all in a UIScrollView (a form essentially). Instead of the textView automatically expanding with the content, I have a button underneath which I would like the user to be able to click and expand/colapse the textView.
Here is what I have:
var textViewIsExpanded: Bool = false {
didSet {
if self.textViewIsExpanded {
self.expandTextViewButton.isSelected = true
guard self.myTextView.contentSize.height > 70 else { return }
self.myTextView.isScrollEnabled = false
self.myTextView.translatesAutoresizingMaskIntoConstraints = true
self.myTextView.sizeThatFits(CGSize(width: self.scrollView.width - 24, height: CGFloat.greatestFiniteMagnitude))
} else {
self.expandTextViewButton.isSelected = false
self.myTextView.isScrollEnabled = true
self.myTextView.translatesAutoresizingMaskIntoConstraints = false
}
}
}
#IBAction func expandTextViewButtonTapped(_ sender: UIButton) {
textViewIsExpanded.toggle()
}
I have tried .sizeToFit() in place of .sizeThatFits(...) which sort of worked but it resized the width along with the height and I am only looking to expand/colapse the height. I'm guessing it is a matter of correctly implementing the CGSize and/or IB constraints but I am not able to land on a solution that works how I want.

Answer 1

First, it's a bad idea to toggle .translatesAutoresizingMaskIntoConstraints between true and false.
What you probably want is to give your text view a Height constraint of 70... connect it to an #IBOutlet... and then toggle .isActive on that constraint.
Second, if you have only one line of text, so the content size height is, maybe, 30, and then you call
textViewIsExpanded = true
your code as-is will set textViewIsExpanded to true but will leave .isScrollEnabled true --- so it won't really be "expanded".
Third, you need to let auto-layout know that you're changing the sizing behavior of the text view by calling:
self.myTextView.invalidateIntrinsicContentSize()
after toggling .isScrollEnabled.
So, add and connect a property for your text view's height constraint:
#IBOutlet var textViewHeightConstraint: NSLayoutConstraint!
and try changing your code to this:
var textViewIsExpanded: Bool = false {
didSet {
if self.textViewIsExpanded {
// if contentSize.height is less-than 71
// reset to false
if self.myTextView.contentSize.height < 71 {
self.textViewIsExpanded = false
return
} else {
self.expandTextViewButton.isSelected = true
self.myTextView.isScrollEnabled = false
self.textViewHeightConstraint.isActive = false
}
} else {
self.expandTextViewButton.isSelected = false
self.myTextView.isScrollEnabled = true
self.textViewHeightConstraint.isActive = true
}
self.myTextView.invalidateIntrinsicContentSize()
}
}