Cant Change UIView Background Color From Black

Question

This is my first time in which I've encountered problems with drawRect. I have a simple UIView subclass with a path to fill. Everything is fine. The path gets filled properly, but the background remains black no matter what. What should I do? My code is listed below:

var color: UIColor = UIColor.red {didSet{setNeedsDisplay()}}

private var spaceshipBezierPath: UIBezierPath{
    let path = UIBezierPath()
    let roomFromTop: CGFloat = 10
    let roomFromCenter: CGFloat = 7
    path.move(to: CGPoint(x: bounds.minX, y: bounds.maxY))
    path.addLine(to: CGPoint(x: bounds.minX, y: bounds.minY+roomFromTop))
    path.addLine(to: CGPoint(x: bounds.midX-roomFromCenter, y: bounds.minY+roomFromTop))
    path.addLine(to: CGPoint(x: bounds.midX-roomFromCenter, y: bounds.minY))
    path.addLine(to: CGPoint(x: bounds.midX+roomFromCenter, y: bounds.minY))
    path.addLine(to: CGPoint(x: bounds.midX+roomFromCenter, y: bounds.minY+roomFromTop))
    path.addLine(to: CGPoint(x: bounds.maxX, y: bounds.minY+roomFromTop))
    path.addLine(to: CGPoint(x: bounds.maxX, y: bounds.maxY))
    path.addLine(to: CGPoint(x: bounds.minX, y: bounds.maxY))
    return path
}

override func draw(_ rect: CGRect) {
    color.setFill()
    spaceshipBezierPath.fill()
}

Here is what the view looks like:

I'm not sure but maybe add a `path.close()` before return path in spaceshipBezierPath — Grifas, Jan 15 '17 at 21:01
Nope. Tried that but didn't work. Thanks for the help though — Nikhil Sridhar, Jan 15 '17 at 21:11
@Nikhi Sridhar, I use your code to draw the rect but get the color, your red is blue in my view, your black is white. and what effect do you want to get? — aircraft, Jan 16 '17 at 00:02

matt · Accepted Answer · 2017-01-16T03:14:28.613

I have a simple UIView subclass ... but the background remains black no matter what

Typically that sort of thing is because you have forgotten to set the UIView subclass's isOpaque to false. It is a good idea to do this in the UIView subclass's initializer in order for it to be early enough.

For example, here I've adapted your code very slightly. This is the complete code I'm using:

class MyView : UIView {
    private var spaceshipBezierPath: UIBezierPath{
        let path = UIBezierPath()
        // ... identical to your code
        return path
    }
    override func draw(_ rect: CGRect) {
        UIColor.red.setFill()
        spaceshipBezierPath.fill()
    }
}

class ViewController: UIViewController {
    override func viewDidLoad() {
        super.viewDidLoad()        
        let v = MyView(frame:CGRect(x: 100, y: 100, width: 200, height: 200))
        self.view.addSubview(v)
    }
}

Notice the black background:

Now I add these lines to MyView:

override init(frame:CGRect) {
    super.init(frame:frame)
    self.isOpaque = false
}
required init?(coder aDecoder: NSCoder) {
    fatalError("init(coder:) has not been implemented")
}

See the difference that makes?

Would it be a valid alternative to set `isOpaque` in `willMove(toSuperview)` e.g.? — andreas1724, Apr 15 '21 at 20:52
@andreas1724 Absolutely, I think so — if it is called for your situation. That should be "early enough" too. — matt, Apr 15 '21 at 21:00

score 1 · Answer 2 · answered Sep 21 '20 at 15:01

1

In my case what I solved was to switch from Background-Color "No Color", to Background-Color "Clear Color"

answered Sep 21 '20 at 15:01

Andreas

185
7

score 0 · Answer 3 · answered Feb 27 '19 at 23:40

For future seekers....

I had the same problem but @matt solution didn’t work for me.

In my scenario, I had a UIView (A) behind another UIView (B). UIView (A) had a background color and UIView (B) was transparent. Worth to note that B was subclassed to create a custom shape using UIBezier by overriding draw method.

Turned out that in this situation a transparent UIView means nothing and I had to set the same background color for B or either remove background color of A.

there was no other way, so don’t waste your time if you have the same scenario!

Cant Change UIView Background Color From Black

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