Swift: How to resize the font size within a UITextView while using AutoLayout?

Question

I am one week into Swift programing and I want to build my first Application with Autolayout. The current state of my app is that I generate a bunch of PictureCell in my ViewController. Their size is based on a slider value (and also calculated in the ViewController). This works just fine.

My struggle is customizing the inside of my PictureCell. My goal is to have a Label in the cell which font size is automatically resized when I resize the cell.

At the current state I can resize the Cell and the UITextView like I want, but I cannot resize the font within the Textview because it's constant is just called when it is initialized (I guess).

How can I address this problem in a good way?

Due to a not understanding of Swifts logic I have to post the whole code of the PictureCell:

class PictureCell: UICollectionViewCell {
override init(frame: CGRect) {
    super.init(frame: frame)
    self.translatesAutoresizingMaskIntoConstraints = false
    self.layer.cornerRadius = self.bounds.width / 20
    self.clipsToBounds = true

    setupViews()
}

let descriptionTextView: UITextView = {
    let textView = UITextView()
    textView.text = "Header"
    textView.textColor = .black
    textView.backgroundColor = .white
    textView.translatesAutoresizingMaskIntoConstraints = false
    textView.textAlignment = .center
    textView.isEditable = false
    textView.isScrollEnabled = false
    textView.sizeToFit()
    textView.font = UIFont.boldSystemFont(ofSize: textView.contentSize.height / 2) // Resize that

    textView.layer.borderWidth = 2
    textView.layer.borderColor = UIColor.red.cgColor

    return textView
}()


var mainPicture: UIImageView = {
    let imageView = UIImageView()
    imageView.contentMode = .scaleAspectFill
    imageView.autoresizingMask = [.flexibleWidth, .flexibleHeight]
    imageView.clipsToBounds = true

    return imageView
}()

 func setPictureForIndex(index: Int)  {
    self.mainPicture.image = UIImage(named: "color\(index)")
}

func setupViews() {
    addSubview(mainPicture)
    confMainPicture()

    addSubview(descriptionTextView)
    confDescriptionTextView()
}

func confMainPicture() {
    mainPicture.translatesAutoresizingMaskIntoConstraints = false
    mainPicture.widthAnchor.constraint(equalTo: self.widthAnchor).isActive = true
    mainPicture.heightAnchor.constraint(equalTo: self.heightAnchor).isActive = true
    mainPicture.topAnchor.constraint(equalTo: self.topAnchor).isActive = true
    mainPicture.bottomAnchor.constraint(equalTo: self.bottomAnchor).isActive = true
}

func confDescriptionTextView(){
    descriptionTextView.translatesAutoresizingMaskIntoConstraints = false
    descriptionTextView.widthAnchor.constraint(equalTo: self.widthAnchor).isActive = true
    descriptionTextView.heightAnchor.constraint(equalTo: mainPicture.heightAnchor, multiplier: 0.25).isActive = true
    descriptionTextView.topAnchor.constraint(equalTo: self.topAnchor).isActive = true
}

Too small for the text

Just fine

Too big to look good

Answer 1

This Code solved my problem more or less: It doesn't work properly if the Cell is really small but it's better than the starting point and maybe someone can use it.

class PictureCell: UICollectionViewCell {
override init(frame: CGRect) {
    super.init(frame: frame)
    self.translatesAutoresizingMaskIntoConstraints = false
    self.layer.cornerRadius = self.bounds.width / 20
    self.clipsToBounds = true
    setupViews()
}
//MARK: -

var cellIdetifier = Int()

var mainPicture: UIImageView = {
    let imageView = UIImageView()
    imageView.contentMode = .scaleAspectFill
    imageView.autoresizingMask = [.flexibleWidth, .flexibleHeight]
    imageView.clipsToBounds = true
    imageView.layer.cornerRadius = imageView.bounds.width / 20
    return imageView
}()

var descriptionBox: UIView = {
    let descVie = UIView()
    descVie.backgroundColor = UIColor(red: 0.1 , green: 0.1, blue: 0.1, alpha: 0.5)
    descVie.layer.borderWidth = 0.5
    descVie.layer.borderColor = UIColor.black.cgColor
    descVie.clipsToBounds = true
    descVie.layer.cornerRadius = descVie.bounds.height / 5
    return descVie
}()

lazy var descLabel: UITextField = {
    let label = UITextField()
    label.textColor = .white
    label.textAlignment = .center
    label.clipsToBounds = true
    label.font = UIFont.systemFont(ofSize: 15)
    label.adjustsFontSizeToFitWidth = true
    label.autoresizingMask = [.flexibleWidth,.flexibleHeight]
    label.sizeToFit()
    label.layoutIfNeeded()
    label.isUserInteractionEnabled = false
    return label
}()

func setPictureForIndex(index: Int, name: String)  {
    self.descLabel.text = name
    self.mainPicture.image = UIImage(named: "color\(index)")
}
// MARK: -
// MARK: Layout
func setupViews() {
    addSubview(mainPicture)
    addSubview(descriptionBox)
    descriptionBox.addSubview(descLabel)
    confBounds()
}

func confBounds() {
    mainPicture.translatesAutoresizingMaskIntoConstraints = false
    mainPicture.widthAnchor.constraint(equalTo: self.widthAnchor).isActive = true
    mainPicture.heightAnchor.constraint(equalTo: self.heightAnchor).isActive = true
    mainPicture.topAnchor.constraint(equalTo: self.topAnchor).isActive = true
    mainPicture.bottomAnchor.constraint(equalTo: self.bottomAnchor).isActive = true

    descriptionBox.translatesAutoresizingMaskIntoConstraints = false
    descriptionBox.widthAnchor.constraint(equalTo: self.widthAnchor).isActive = true
    descriptionBox.heightAnchor.constraint(equalTo: mainPicture.heightAnchor, multiplier: 0.25).isActive = true
    descriptionBox.topAnchor.constraint(equalTo: self.topAnchor).isActive = true
    descriptionBox.bottomAnchor.constraint(greaterThanOrEqualTo: mainPicture.topAnchor, constant: 1)

    descLabel.translatesAutoresizingMaskIntoConstraints = false
    descLabel.widthAnchor.constraint(equalTo: descriptionBox.widthAnchor).isActive = true
    descLabel.heightAnchor.constraint(equalTo: descriptionBox.heightAnchor).isActive = true
    descLabel.bottomAnchor.constraint(equalTo: descriptionBox.bottomAnchor).isActive = true
    descLabel.heightAnchor.constraint(equalTo: descriptionBox.heightAnchor).isActive = true
}

}