Auto-sizing a UILabel without setting an explicit height - ios

Question

How do I get a multi-line label to size itself? I don't want to set an explicit height for it but I do need to place it in view.
The way my app is built, we explicitly set frames and origins rather than using NSLayoutConstraints. It's a mature app so this isn't up for discussion.
I'd like to be able to give my UILabel an origin and a width and let it figure its own height out.
How can I do this? This is my playground code:
let view = UIView(frame: CGRect(x: 0, y: 0, width: 300, height: 180))
view.backgroundColor = .white
let l = UILabel()
l.text = "this is a really long label that should wrap around and stuff. it should maybe wrap 2 or three times i dunno"
l.textColor = .black
l.lineBreakMode = .byWordWrapping
l.numberOfLines = 0
l.textAlignment = .center
l.sizeToFit()
let margin: CGFloat = 60
view
view.addSubview(l)
l.frame = CGRect(x: margin, y: 0, width: view.bounds.width - (margin * 2), height: 100)
// I don't want to do this ^^

Answer 1

This may do what you want...
As requested, you want to set the .origin and .width of a UILabel and have it set its own .height based on the text.
class ZackLabel: UILabel {
override public func layoutSubviews() {
super.layoutSubviews()
let h = sizeThatFits(CGSize(width: self.bounds.width, height: CGFloat.greatestFiniteMagnitude))
self.frame.size.height = h.height
}
}
class ViewController: UIViewController {
var testLabel: ZackLabel!
override func viewDidLoad() {
super.viewDidLoad()
view.backgroundColor = .yellow
// instantiate a 300 x 180 UIView at 20, 80
let myView = UIView(frame: CGRect(x: 20, y: 80, width: 300, height: 180))
myView.backgroundColor = .white
// instantiate a ZackLabel
testLabel = ZackLabel()
testLabel.text = "this is a really long label that should wrap around and stuff. it should maybe wrap 2 or three times i dunno"
testLabel.textColor = .black
testLabel.lineBreakMode = .byWordWrapping
testLabel.numberOfLines = 0
testLabel.textAlignment = .center
// set background color so we can see its frame
testLabel.backgroundColor = .cyan
let margin: CGFloat = 60
// set label's origin
testLabel.frame.origin = CGPoint(x: margin, y: 0)
// set label's width (label will set its own height)
testLabel.frame.size.width = myView.bounds.width - margin * 2
// add the view
view.addSubview(myView)
// add the label to the view
myView.addSubview(testLabel)
// add a tap recognizer so we can change the label's text at run-time
let rec = UITapGestureRecognizer(target: self, action: #selector(tapFunc(_:)))
view.addGestureRecognizer(rec)
}
#objc func tapFunc(_ sender: UITapGestureRecognizer) -> Void {
testLabel.text = "This is dynamic text being set."
}
}
Result (on an iPhone 8):
and, after tapping on the (yellow) view, dynamically changing the text:

Answer 2

label.sizeThatFits(CGSize(width: <your required width>, height: CGFloat.greatestFiniteMagnitude))
This returns the labels needed size, growing infinitely in height, but fitted to your required width. I've occasionally noticed minor inaccuracies with this function (rounding error?), so I tend to bump the width and height by 1 just to be safe.

Answer 3

UILabel comes with an intrinsic size that should be calculated based on the text and the label's .font property. You may need to add a margin to it...
var height = l.intrinsicContentSize.height
height += margin
l.frame = CGRect(x: margin, y: 0, width: view.bounds.width - (margin * 2), height: height)
Failing that, maybe you can try something like:
let size = CGSize(width: view.bounds.width - (margin * 2), height: 1000)
let options = NSStringDrawingOptions.usesFontLeading.union(.usesLineFragmentOrigin)
var estimatedFrame = CGRect()
if let font = l.font {
estimatedFrame = NSString(string: l.text).boundingRect(with: size, options: options, attributes: [NSAttributedString.Key.font: font], context: nil)
}
//if you need a margin:
estimatedFrame.height += margin
l.frame = estimatedFrame

Answer 4

Give your UILabel as a UIScrollview or UITableView cell subview.
Then you setup UILabel leading, tralling, top, bottom constrain.
If you give UITableview then set table view hight auto dynamic. If you give UIScrollview
just set UILabel bottom constrain priority low