Custom view is not visible when adding it programatically, but it's visible when it's added using storyboards

Question

I have my own custom view that acts like a progress bar. Here is the code for it:

class ProgressBar: UIView {

    var bottomProgressBar = CAShapeLayer()
    var topProgressBar = CAShapeLayer()

    override init(frame: CGRect) {
        super.init(frame: frame)
        configure()
    }

    required init?(coder aDecoder: NSCoder) {
        super.init(coder: aDecoder)
        configure()
    }

    func configure() {
        bottomProgressBar.strokeColor = UIColor.white.cgColor
        bottomProgressBar.opacity = 0.1
        bottomProgressBar.lineWidth = self.frame.height
        bottomProgressBar.strokeStart = 0
        bottomProgressBar.strokeEnd = 1
        self.layer.addSublayer(bottomProgressBar)

        topProgressBar.strokeColor = UIColor.white.cgColor
        topProgressBar.lineWidth = self.frame.height
        topProgressBar.strokeStart = 0
        topProgressBar.strokeEnd = 1
        self.layer.addSublayer(topProgressBar)

        animate(toValue: 0)
    }

    override func layoutSubviews() {
        super.layoutSubviews()

        let path = UIBezierPath()
        path.move(to: CGPoint(x: 0, y: 0))
        path.addLine(to: CGPoint(x: self.frame.width, y: 0))

        bottomProgressBar.path = path.cgPath
        topProgressBar.path = path.cgPath
    }
}

Now, when I add this using storyboards, by adding an UIView inside the controller and setting the Custom Class to ProgressBar I can see it visible when running the app (it should have a white color with alpha 0.1).

But when I'm trying to added programatically , it's not visible at all. Only if I explicitly set the background color:

myProgressBar.backgroudColor = .red

This is not what I want. I want it to have the white color and alpha 0.1 that is the initial value.

Here is my code for adding it programatically:

var progressBar = ProgressBar()

    override func viewDidLoad() {
        super.viewDidLoad()

        view.addSubview(progressBar)

        progressBar.translatesAutoresizingMaskIntoConstraints = false
        NSLayoutConstraint(item: progressBar, attribute: NSLayoutAttribute.centerX, relatedBy: NSLayoutRelation.equal, toItem: view, attribute: NSLayoutAttribute.centerX, multiplier: 1, constant: 0).isActive = true
        NSLayoutConstraint(item: progressBar, attribute: NSLayoutAttribute.centerY, relatedBy: NSLayoutRelation.equal, toItem: view, attribute: NSLayoutAttribute.centerY, multiplier: 1, constant: 0).isActive = true
        NSLayoutConstraint(item: progressBar, attribute: NSLayoutAttribute.width, relatedBy: NSLayoutRelation.equal, toItem: nil, attribute: NSLayoutAttribute.notAnAttribute, multiplier: 1, constant: 100).isActive = true
        NSLayoutConstraint(item: progressBar, attribute: NSLayoutAttribute.height, relatedBy: NSLayoutRelation.equal, toItem: nil, attribute: NSLayoutAttribute.notAnAttribute, multiplier: 1, constant: 1).isActive = true
    }

I don't seem to understand what is the difference between adding it using storyboards and adding it programatically.
I see that the constraints are correct and the view is added, but why doesn't the default color appear ?

Does anyone have an idea what my issue is in this case ?

edit:

Added code for the animate method:

func animate(toValue: Double) {
    let animation = CABasicAnimation(keyPath: "strokeEnd")

    animation.duration = 1.0
    animation.fromValue = 0
    animation.toValue = toValue

    topProgressBar.strokeEnd = CGFloat(toValue)
    topProgressBar.animation(forKey: "animate")
}

I'd recommend double-checking the constraints, if you take a screenshot in emulator, it might exist but not be on screen or the proper size — SQLiteNoob
– SQLiteNoob, Commented Feb 17, 2018 at 14:25
I put the same constraints in code as in storyboard where it works. If I change the color to red, I can see them, perfect. But that is not what I want. — Adrian
– Adrian, Commented Feb 17, 2018 at 17:22

Bilal · Accepted Answer · 2018-02-17 19:52:00Z

2

+100

Problem starts with this var progressBar = ProgressBar(). This invokes the init method and configure() is called. At this point ProgressBar frame width and height is zero.

In your configure() method your are setting line widths.

bottomProgressBar.lineWidth = self.frame.height // 0
topProgressBar.lineWidth = self.frame.height // 0

So lines width are set to zero and thats way it's not being displayed.

To fix this you must update the CAShapeLayer line widths in layoutSubviews() method.

override func layoutSubviews() {
    super.layoutSubviews()

    let path = UIBezierPath()
    path.move(to: CGPoint(x: 0, y: 0))
    path.addLine(to: CGPoint(x: self.frame.width, y: 0))

    bottomProgressBar.lineWidth = self.frame.height // Update lineWidth
    topProgressBar.lineWidth = self.frame.height    // Update lineWidth

    bottomProgressBar.path = path.cgPath
    topProgressBar.path = path.cgPath
}

Why it works for storyboard? Because frame has been set already before configure is called. You can print the frame size in configure and see the difference in both scenarios.

edited Feb 17, 2018 at 19:52

answered Feb 17, 2018 at 19:44

Bilal

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1 Comment

Adrian Over a year ago

Thanks a lot. It's working now. I will award the bounty when it becomes eligible.

Shehata Gamal · Accepted Answer · 2017-12-29 13:45:32Z

0

It's always a bug in display for custom views, You can add this to viewDidLoad

 self.progressBar.setNeedsDisplay()

Edit:

you can add this line to configure method default background color for the view as the default is transparent

 self.backgroundColor = UIColor.red

I see all colors are white so it's usual not to see anything

edited Dec 29, 2017 at 13:45

answered Dec 29, 2017 at 12:32

Shehata Gamal

101k8 gold badges75 silver badges95 bronze badges

8 Comments

Adrian Over a year ago

Still doesn't work for me, even if I add that line .

Shehata Gamal Over a year ago

what's inside that animate(toValue: 0)

Adrian Over a year ago

I updated the question with the code. I also try to delete that line inside configure() and still is the same issue. So I am not sure that there is a problem with that method.

Shehata Gamal Over a year ago

it's not a good practice to add animation while you configure the view for display , If you can move that code to viewDidAppear of the mainViewController

Adrian Over a year ago

Still, same issue. Not sure else can I do.

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