How can I center UIView in a custom control? - ios

Question

I'm working on a exercise to create a custom control of anything. My idea is to have a UIView in the middle of the screen and a UILabel below it. When you tap on the view a random color will appear with the label changing to its hex value. When trying to create this custom control I'm having a problem trying to center the UIView programmatically. I get to an issue at `colorBox.center~
import UIKit
#IBDesignable
class Color: UIView {
private lazy var label : UILabel = {
let label = UILabel()
label.backgroundColor = UIColor.clear
label.translatesAutoresizingMaskIntoConstraints = false
label.heightAnchor.constraint(equalToConstant: 25.0).isActive = true
label.widthAnchor.constraint(equalToConstant: 100.0).isActive = true
label.font = .systemFont(ofSize: 15.0, weight: UIFontWeightRegular)
return label
}()
private lazy var colorGen : UIView = {
let colorBox = UIView()
colorBox.backgroundColor = UIColor.black
colorBox.heightAnchor.constraint(equalToConstant: 100.0).isActive = true
colorBox.widthAnchor.constraint(equalToConstant: 100.0).isActive = true
colorBox.centerXAnchor.constraint(equalTo: colorBox.frame.size.width /2)
}()
override init (frame: CGRect) {
super.init(frame:frame)
setUpLabel()
setUpView()
}
required init?(coder: NSCoder) {
super.init(coder: coder)
setUpLabel()
setUpView()
}
I've tried the answers about using self.view but it doesn't work for me so I'm a bit lost.

Answer 1

You're close, but you need to add the label and the view so you can then constrain them relative to the superview...
#IBDesignable
class ColorView: UIView {
private lazy var colorLabel : UILabel = {
let label = UILabel()
label.translatesAutoresizingMaskIntoConstraints = false
label.backgroundColor = UIColor.clear
label.heightAnchor.constraint(equalToConstant: 25.0).isActive = true
label.widthAnchor.constraint(equalToConstant: 100.0).isActive = true
label.font = .systemFont(ofSize: 15.0, weight: UIFontWeightRegular)
return label
}()
private lazy var colorGen : UIView = {
let colorBox = UIView()
colorBox.translatesAutoresizingMaskIntoConstraints = false
colorBox.backgroundColor = UIColor.cyan
colorBox.heightAnchor.constraint(equalToConstant: 100.0).isActive = true
colorBox.widthAnchor.constraint(equalToConstant: 100.0).isActive = true
return colorBox
}()
override init (frame: CGRect) {
super.init(frame:frame)
commonSetup()
}
required init?(coder: NSCoder) {
super.init(coder: coder)
commonSetup()
}
func commonSetup() -> Void {
self.addSubview(colorGen)
self.addSubview(colorLabel)
colorGen.leftAnchor.constraint(equalTo: self.leftAnchor, constant: 0.0).isActive = true
colorGen.rightAnchor.constraint(equalTo: self.rightAnchor, constant: 0.0).isActive = true
colorGen.topAnchor.constraint(equalTo: self.topAnchor, constant: 0.0).isActive = true
colorLabel.leftAnchor.constraint(equalTo: self.leftAnchor, constant: 0.0).isActive = true
colorLabel.rightAnchor.constraint(equalTo: self.rightAnchor, constant: 0.0).isActive = true
colorLabel.bottomAnchor.constraint(equalTo: self.bottomAnchor, constant: 0.0).isActive = true
colorLabel.topAnchor.constraint(equalTo: colorGen.bottomAnchor, constant: 0.0).isActive = true
colorLabel.text = "the label"
}
}