How to make the view height resizable in Swift? - ios

Question

I have a custom UIView class where I'm creating a UIView and putting inside UILabel. Initially, I set UIView height equal to 60.0. But how can I do that my UIView height would resize with UILabel? For example if UILabel contains 5 linesof text UIView height will also increase to 200pt(for example).
Here is my class: https://gist.github.com/orkhanalizade/747dc4fd1eb9f228ac964fb4048125dc
I have tried
self.translatesAutoresizingMaskIntoConstraints = false
self.heightAnchor.constraint(greaterThanOrEqualToConstant: 60.0).isActive = true
NSLayoutConstraint(item: self, attribute: .top, relatedBy: .equal, toItem: self, attribute: .top, multiplier: 1.0, constant: 60.0).isActive = true
but it did not help me
What I do wrong and how can I fix it?

Answer 1

Since you are resizing the constants, you may want to use layoutIfNeeded(). It will force update the constraints in the view. You can read more about it in Apple's documentation.

Answer 2

Just calculate the height according to text and update height constraint of UIView with UIView.animate() method.

Answer 3

Couple notes...
1) In general, a view should not set its own frame. What happens if you want to add MyView as a subview of another view? Setting its frame as you have:
width: UIScreen.main.bounds.width - 16.0
will not give you the desired results.
2) You do not need:
self.addConstraints(constraints)
3) I find it helpful to give elements different, obvious background colors -- makes it easy to see what the frames are doing.
Here is an edited version of your gist, along with a view controller to add / display it:
import UIKit
class MyView: UIView {
var label: UILabel!
var text: String? {
didSet {
label.text = text
}
}
var cornerRadius: CGFloat = 0.0 {
didSet {
self.layer.cornerRadius = self.cornerRadius
self.layer.masksToBounds = true
}
}
var textColor: UIColor = UIColor.black {
didSet {
label.textColor = textColor
}
}
var isTextCentered: Bool = false {
didSet {
self.label.textAlignment = isTextCentered ? .center : .left
}
}
init() {
// we'll be using constraints, so no need to set a frame
super.init(frame: CGRect.zero)
initialize()
}
required init?(coder aDecoder: NSCoder) {
fatalError("init(coder:) has not been implemented")
}
fileprivate func initialize() {
label = UILabel()
label.translatesAutoresizingMaskIntoConstraints = false
label.numberOfLines = 0
self.addSubview(label)
let constraints = [
NSLayoutConstraint(item: label, attribute: .top, relatedBy: .equal, toItem: self, attribute: .top, multiplier: 1.0, constant: 8.0),
NSLayoutConstraint(item: label, attribute: .leading, relatedBy: .equal, toItem: self, attribute: .leading, multiplier: 1.0, constant: 8.0),
NSLayoutConstraint(item: label, attribute: .trailing, relatedBy: .equal, toItem: self, attribute: .trailing, multiplier: 1.0, constant: -8.0),
NSLayoutConstraint(item: label, attribute: .bottom, relatedBy: .equal, toItem: self, attribute: .bottom, multiplier: 1.0, constant: -8.0)
]
NSLayoutConstraint.activate(constraints)
// so we can see self's frame
self.backgroundColor = .red
// so we can see label's frame
label.backgroundColor = .yellow
}
}
class ViewController: UIViewController {
override func viewDidLoad() {
super.viewDidLoad()
// instantiate the custom view
let v = MyView()
// we'll be using constraints
v.translatesAutoresizingMaskIntoConstraints = false
// add the view
view.addSubview(v)
NSLayoutConstraint.activate([
// constrain Top: 60 / Leading: 8 / Trailing: -8
v.topAnchor.constraint(equalTo: view.safeAreaLayoutGuide.topAnchor, constant: 60.0),
v.leadingAnchor.constraint(equalTo: view.safeAreaLayoutGuide.leadingAnchor, constant: 8.0),
v.trailingAnchor.constraint(equalTo: view.safeAreaLayoutGuide.trailingAnchor, constant: -8.0),
// constrain height >= 60
v.heightAnchor.constraint(greaterThanOrEqualToConstant: 60.0),
])
// add 10 lines of text
v.text = (1...10).map({ "Line \($0)" }).joined(separator: "\n")
}
}
And the result: