UITextView with Adjustable Font Size - swift

Question

I tried to make an editable uitextview with centered text that can have a maximum of 2 lines and that automatically adjusts its font size in order to fit its text within a fixed width and height.
My solution: Type some text in a UITextView, automatically copy that text and paste it in a uilabel that itself automatically adjusts its font size perfectly, and then retrieve the newly adjusted font size of the uilabel and set that size on the UITextView text.
I have spent about a month on this and repeatedly failed. I can't find a way to make it work. My attempted textview below glitches some letters out and hides large portions of out-of-bounds text instead of resizing everything. Please help me stack overflow Gods.
My attempt:
import UIKit
class TextViewViewController: UIViewController{
private let editableUITextView: UITextView = {
let tv = UITextView()
tv.font = UIFont.systemFont(ofSize: 20)
tv.text = "Delete red text, and type here"
tv.backgroundColor = .clear
tv.textAlignment = .center
tv.textContainer.maximumNumberOfLines = 2
tv.textContainer.lineBreakMode = .byWordWrapping
tv.textColor = .red
return tv
}()
private let correctTextSizeLabel: UILabel = {
let tv = UILabel()
tv.font = UIFont.systemFont(ofSize: 20)
tv.backgroundColor = .clear
tv.text = "This is properly resized"
tv.adjustsFontSizeToFitWidth = true
tv.lineBreakMode = .byTruncatingTail
tv.numberOfLines = 2
tv.textAlignment = .center
tv.textColor = .green
return tv
}()
override func viewDidLoad() {
super.viewDidLoad()
view.backgroundColor = UIColor.white
view.addSubview(correctTextSizeLabel)
view.addSubview(editableUITextView)
editableUITextView.centerYAnchor.constraint(equalTo: view.centerYAnchor).isActive = true
editableUITextView.centerXAnchor.constraint(equalTo: view.centerXAnchor).isActive = true
editableUITextView.heightAnchor.constraint(equalToConstant: 150).isActive = true
editableUITextView.widthAnchor.constraint(equalToConstant: 150).isActive = true
editableUITextView.translatesAutoresizingMaskIntoConstraints = false
editableUITextView.delegate = self
correctTextSizeLabel.leftAnchor.constraint(equalTo: editableUITextView.leftAnchor).isActive = true
correctTextSizeLabel.rightAnchor.constraint(equalTo: editableUITextView.rightAnchor).isActive = true
correctTextSizeLabel.topAnchor.constraint(equalTo: editableUITextView.topAnchor).isActive = true
correctTextSizeLabel.bottomAnchor.constraint(equalTo: editableUITextView.bottomAnchor).isActive = true
correctTextSizeLabel.translatesAutoresizingMaskIntoConstraints = false
editableUITextView.isScrollEnabled = false
}
func getApproximateAdjustedFontSizeOfLabel(label: UILabel) -> CGFloat {
if label.adjustsFontSizeToFitWidth == true {
var currentFont: UIFont = label.font
let originalFontSize = currentFont.pointSize
var currentSize: CGSize = (label.text! as NSString).size(withAttributes: [NSAttributedString.Key.font: currentFont])
while currentSize.width > label.frame.size.width * 2 && currentFont.pointSize > (originalFontSize * label.minimumScaleFactor) {
currentFont = currentFont.withSize(currentFont.pointSize - 1)
currentSize = (label.text! as NSString).size(withAttributes: [NSAttributedString.Key.font: currentFont])
}
return currentFont.pointSize
} else {
return label.font.pointSize
}
}
}
//MARK: - UITextViewDelegate
extension TextViewViewController : UITextViewDelegate {
private func textViewShouldBeginEditing(_ textView: UITextView) {
textView.becomeFirstResponder()
}
func textViewDidBeginEditing(_ textView: UITextView) {
}
func textViewDidEndEditing(_ textView: UITextView) {
}
func textViewDidChange(_ textView: UITextView) {
textView.becomeFirstResponder()
self.correctTextSizeLabel.text = textView.text
self.correctTextSizeLabel.isHidden = false
let estimatedTextSize = self.getApproximateAdjustedFontSizeOfLabel(label: self.correctTextSizeLabel)
print("estimatedTextSize: ",estimatedTextSize)
self.editableUITextView.font = UIFont.systemFont(ofSize: estimatedTextSize)
}
}
UITextField's have the option to automatically adjust font size to fit a fixed width but they only allow 1 line of text, I need it to have a maximum of 2. UILabel's solve this problem perfectly but they aren't editable.

Answer 1

After some searching, this looks like it will be very difficult to get working as desired.
This doesn't directly answer your question, but it may be an option:
Here's the example code:
class TestInputViewController: UIViewController {
let testLabel: InputLabel = InputLabel()
override func viewDidLoad() {
super.viewDidLoad()
let instructionLabel = UILabel()
instructionLabel.textAlignment = .center
instructionLabel.text = "Tap yellow label to edit..."
let centeringFrameView = UIView()
// label properties
let fnt: UIFont = .systemFont(ofSize: 32.0)
testLabel.isUserInteractionEnabled = true
testLabel.font = fnt
testLabel.adjustsFontSizeToFitWidth = true
testLabel.minimumScaleFactor = 0.25
testLabel.numberOfLines = 2
testLabel.setContentHuggingPriority(.required, for: .vertical)
let minLabelHeight = ceil(fnt.lineHeight)
// so we can see the frames
centeringFrameView.backgroundColor = .red
testLabel.backgroundColor = .yellow
[centeringFrameView, instructionLabel, testLabel].forEach {
$0.translatesAutoresizingMaskIntoConstraints = false
}
view.addSubview(instructionLabel)
view.addSubview(centeringFrameView)
centeringFrameView.addSubview(testLabel)
let g = view.safeAreaLayoutGuide
NSLayoutConstraint.activate([
// instruction label centered at top
instructionLabel.topAnchor.constraint(equalTo: g.topAnchor, constant: 20.0),
instructionLabel.centerXAnchor.constraint(equalTo: g.centerXAnchor),
// centeringFrameView 20-pts from instructionLabel bottom
centeringFrameView.topAnchor.constraint(equalTo: instructionLabel.bottomAnchor, constant: 20.0),
// Leading / Trailing with 20-pts "padding"
centeringFrameView.leadingAnchor.constraint(equalTo: g.leadingAnchor, constant: 20.0),
centeringFrameView.trailingAnchor.constraint(equalTo: g.trailingAnchor, constant: -20.0),
// test label centered vertically in centeringFrameView
testLabel.centerYAnchor.constraint(equalTo: centeringFrameView.centerYAnchor, constant: 0.0),
// Leading / Trailing with 20-pts "padding"
testLabel.leadingAnchor.constraint(equalTo: centeringFrameView.leadingAnchor, constant: 20.0),
testLabel.trailingAnchor.constraint(equalTo: centeringFrameView.trailingAnchor, constant: -20.0),
// height will be zero if label has no text,
// so give it a min height of one line
testLabel.heightAnchor.constraint(greaterThanOrEqualToConstant: minLabelHeight),
// centeringFrameView height = 3 * minLabelHeight
centeringFrameView.heightAnchor.constraint(equalToConstant: minLabelHeight * 3.0)
])
// to handle user input
testLabel.editCallBack = { [weak self] str in
guard let self = self else { return }
self.testLabel.text = str
}
testLabel.doneCallBack = { [weak self] in
guard let self = self else { return }
// do something when user taps done / enter
}
let t = UITapGestureRecognizer(target: self, action: #selector(self.labelTapped(_:)))
testLabel.addGestureRecognizer(t)
}
#objc func labelTapped(_ g: UITapGestureRecognizer) -> Void {
testLabel.becomeFirstResponder()
testLabel.inputContainerView.theTextView.text = testLabel.text
testLabel.inputContainerView.theTextView.becomeFirstResponder()
}
}
class InputLabel: UILabel {
var editCallBack: ((String) -> ())?
var doneCallBack: (() -> ())?
override var canBecomeFirstResponder: Bool {
return true
}
override var canResignFirstResponder: Bool {
return true
}
override var inputAccessoryView: UIView? {
get { return inputContainerView }
}
lazy var inputContainerView: CustomInputAccessoryView = {
let customInputAccessoryView = CustomInputAccessoryView(frame: .zero)
customInputAccessoryView.backgroundColor = .blue
customInputAccessoryView.editCallBack = { [weak self] str in
guard let self = self else { return }
self.editCallBack?(str)
}
customInputAccessoryView.doneCallBack = { [weak self] in
guard let self = self else { return }
self.resignFirstResponder()
}
return customInputAccessoryView
}()
}
class CustomInputAccessoryView: UIView, UITextViewDelegate {
var editCallBack: ((String) -> ())?
var doneCallBack: (() -> ())?
let theTextView: UITextView = {
let tv = UITextView()
tv.isScrollEnabled = false
tv.font = .systemFont(ofSize: 16)
tv.autocorrectionType = .no
tv.returnKeyType = .done
return tv
}()
override init(frame: CGRect) {
super.init(frame: frame)
backgroundColor = UIColor.white
autoresizingMask = [.flexibleHeight, .flexibleWidth]
addSubview(theTextView)
theTextView.translatesAutoresizingMaskIntoConstraints = false
NSLayoutConstraint.activate([
// constraint text view with 8-pts "padding" on all 4 sides
theTextView.topAnchor.constraint(equalTo: topAnchor, constant: 8),
theTextView.leadingAnchor.constraint(equalTo: leadingAnchor, constant: 8),
theTextView.trailingAnchor.constraint(equalTo: trailingAnchor, constant: -8),
theTextView.bottomAnchor.constraint(equalTo: bottomAnchor, constant: -8),
])
theTextView.delegate = self
}
func textView(_ textView: UITextView, shouldChangeTextIn range: NSRange, replacementText text: String) -> Bool {
if (text == "\n") {
textView.resignFirstResponder()
doneCallBack?()
}
return true
}
func textViewDidChange(_ textView: UITextView) {
editCallBack?(textView.text ?? "")
}
required init?(coder aDecoder: NSCoder) {
fatalError("init(coder:) has not been implemented")
}
override var intrinsicContentSize: CGSize {
return .zero
}
}