Why doesn't sizeThatFits work with UILabel? - ios

Question

I have a simple class that contains two labels and a line in a stack:
class TestView: UIView
{
let label_A = UILabel()
let label_B = UILabel()
override init(frame: CGRect) { super.init(frame: frame); setup() }
required init?(coder aDecoder: NSCoder) { super.init(coder: aDecoder); setup() }
func setup()
{
let view_BG = UIView()
let view_LineH = UIView()
// Configure
view_BG.backgroundColor = .white
view_BG.layer.cornerRadius = 6
view_LineH.backgroundColor = .gray
label_A.numberOfLines = 0
label_A.backgroundColor = UIColor(red: 1, green: 0, blue: 0, alpha: 0.2)
label_A.textColor = .red
label_B.numberOfLines = 0
label_B.textColor = .blue
label_B.backgroundColor = UIColor(red: 0, green: 0, blue: 1, alpha: 0.2)
label_A.text = "TestA"
label_B.text = "Experiment with Swift standard library types and learn high-level concepts using visualizations and practical examples. Learn how the Swift standard library uses protocols and generics to express powerful constraints. Download the playground below to get started."
// Assemble
self.addSubview(view_BG)
view_BG.addSubview(label_A)
view_BG.addSubview(view_LineH)
view_BG.addSubview(label_B)
// Layout
view_BG.constrain_edges(to: self)
label_A.constrain_edges(to: view_BG, excludingEdge: .bottom)
label_B.constrain_edges(to: view_BG, excludingEdge: .top)
view_LineH.constrain_height(1)
view_LineH.constrain_left(to: view_BG)
view_LineH.constrain_right(to: view_BG)
view_LineH.constrain_topToBottom(of: label_A)
label_B.constrain_topToBottom(of: view_LineH)
}
}
When I call sizeThatFits, it just spits the height back at me:
let v = TestView()
let s = v.sizeThatFits(CGSize(width: 200, height: 10000))
// s is (200, 10000)
How can I calculate the desired height with a given width?

Answer 1

I believe you want .systemLayoutSizeFitting():
let tv = TestView()
let targSize = CGSize(width: 200, height: 10000)
let fitSize = tv.systemLayoutSizeFitting(targSize, withHorizontalFittingPriority: 1000, verticalFittingPriority: 1)
print(fitSize)
// prints "(200.0, 245.0)" in my playground
I don't have whatever you are using for .constrain_edges stuff, so here is the actual view class I'm running:
class TestView: UIView
{
let label_A = UILabel()
let label_B = UILabel()
override init(frame: CGRect) { super.init(frame: frame); setup() }
required init?(coder aDecoder: NSCoder) { super.init(coder: aDecoder); setup() }
func setup()
{
let view_BG = UIView()
let view_LineH = UIView()
// Configure
view_BG.backgroundColor = .white
view_BG.layer.cornerRadius = 6
view_LineH.backgroundColor = .gray
label_A.numberOfLines = 0
label_A.backgroundColor = UIColor(red: 1, green: 0, blue: 0, alpha: 0.2)
label_A.textColor = .red
label_B.numberOfLines = 0
label_B.textColor = .blue
label_B.backgroundColor = UIColor(red: 0, green: 0, blue: 1, alpha: 0.2)
label_A.text = "TestA"
label_B.text = "Experiment with Swift standard library types and learn high-level concepts using visualizations and practical examples. Learn how the Swift standard library uses protocols and generics to express powerful constraints. Download the playground below to get started."
// Assemble
self.addSubview(view_BG)
view_BG.addSubview(label_A)
view_BG.addSubview(view_LineH)
view_BG.addSubview(label_B)
view_BG.translatesAutoresizingMaskIntoConstraints = false
label_A.translatesAutoresizingMaskIntoConstraints = false
label_B.translatesAutoresizingMaskIntoConstraints = false
view_LineH.translatesAutoresizingMaskIntoConstraints = false
// Layout
view_BG.topAnchor.constraint(equalTo: self.topAnchor, constant: 0.0).isActive = true
view_BG.leftAnchor.constraint(equalTo: self.leftAnchor, constant: 0.0).isActive = true
view_BG.rightAnchor.constraint(equalTo: self.rightAnchor, constant: 0.0).isActive = true
view_BG.bottomAnchor.constraint(equalTo: self.bottomAnchor, constant: 0.0).isActive = true
label_A.topAnchor.constraint(equalTo: view_BG.topAnchor, constant: 0.0).isActive = true
label_A.leftAnchor.constraint(equalTo: view_BG.leftAnchor, constant: 0.0).isActive = true
label_A.rightAnchor.constraint(equalTo: view_BG.rightAnchor, constant: 0.0).isActive = true
label_B.leftAnchor.constraint(equalTo: view_BG.leftAnchor, constant: 0.0).isActive = true
label_B.rightAnchor.constraint(equalTo: view_BG.rightAnchor, constant: 0.0).isActive = true
label_B.bottomAnchor.constraint(equalTo: view_BG.bottomAnchor, constant: 0.0).isActive = true
view_LineH.leftAnchor.constraint(equalTo: view_BG.leftAnchor, constant: 0.0).isActive = true
view_LineH.rightAnchor.constraint(equalTo: view_BG.rightAnchor, constant: 0.0).isActive = true
view_LineH.topAnchor.constraint(equalTo: label_A.bottomAnchor, constant: 0.0).isActive = true
label_B.topAnchor.constraint(equalTo: view_LineH.bottomAnchor, constant: 0.0).isActive = true
view_LineH.heightAnchor.constraint(equalToConstant: 1.0).isActive = true
}
}