问题
First post on stackoverflow so, first and foremost, hello!
I'm trying my hand at Swift for the first time and am working a project and just needed some help on a problem I'm having. I've got a circle using a UIBezierPath that I'd like to change the color of, dynamically. However, when I try to even "hard code" the color, I'm unable to get it to change. I've tried looking here: How to change the color of a UIBezierPath in Swift?, but it didn't answer my question. However, I do see that one answer there does state that a Bezier path has no color. If so, how would I then go about altering the color of the circle going along its path?
Here's the code I'm working with:
outerCircle.path = UIBezierPath(ovalInRect: CGRect(x: 0.0, y: 0.0, width: frameSize.width, height: frameSize.height)).CGPath
outerCircle.lineWidth = 8.0
outerCircle.strokeStart = 0.0
outerCircle.strokeEnd = 0.45
outerCircle.lineCap = kCALineCapRound
outerCircle.fillColor = UIColor.clearColor().CGColor
outerCircle.strokeColor = UIColor.grayColor().CGColor
outerCircleView.layer.addSublayer(outerCircle)
outerCircle.strokeStart = 0.0
outerCircle.strokeEnd = 1.0
vibrancyView.contentView.addSubview(outerCircleView)
innerCircleView.frame.size = frameSize
let innerCirclePadding: CGFloat = 12
innerCircle.path = UIBezierPath(ovalInRect: CGRect(x: innerCirclePadding, y: innerCirclePadding, width: frameSize.width - 2*innerCirclePadding, height: frameSize.height - 2*innerCirclePadding)).CGPath
innerCircle.lineWidth = 4.0
innerCircle.strokeStart = 0.5
innerCircle.strokeEnd = 0.9
innerCircle.lineCap = kCALineCapRound
innerCircle.fillColor = UIColor.clearColor().CGColor
innerCircle.strokeColor = UIColor.grayColor().CGColor
innerCircleView.layer.addSublayer(innerCircle)
Again, I apologize if this is an obvious answer or has already been answered. I appreciate any advice that would help point me in the right direction. Thank you.
UPDATE: So here's what I tried doing. I changed the fill and stroke colors of both inner and outer circles to green, but I still have clear circles:
outerCircle.path = UIBezierPath(ovalInRect: CGRect(x: 0.0, y: 0.0, width: frameSize.width, height: frameSize.height)).CGPath
outerCircle.lineWidth = 8.0
outerCircle.strokeStart = 0.0
outerCircle.strokeEnd = 0.45
outerCircle.lineCap = kCALineCapRound
outerCircle.fillColor = UIColor.greenColor().CGColor
outerCircle.strokeColor = UIColor.greenColor().CGColor
outerCircleView.layer.addSublayer(outerCircle)
outerCircle.strokeStart = 0.0
outerCircle.strokeEnd = 1.0
vibrancyView.contentView.addSubview(outerCircleView)
innerCircleView.frame.size = frameSize
let innerCirclePadding: CGFloat = 12
innerCircle.path = UIBezierPath(ovalInRect: CGRect(x: innerCirclePadding, y: innerCirclePadding, width: frameSize.width - 2*innerCirclePadding, height: frameSize.height - 2*innerCirclePadding)).CGPath
innerCircle.lineWidth = 4.0
innerCircle.strokeStart = 0.5
innerCircle.strokeEnd = 0.9
innerCircle.lineCap = kCALineCapRound
innerCircle.fillColor = UIColor.greenColor().CGColor
innerCircle.strokeColor = UIColor.greenColor().CGColor
innerCircleView.layer.addSublayer(innerCircle)
I'd like to have the circles change colors.
回答1:
A path has no color. It's a path! Only a graphics context has a stroke color / fill color. Sooner or later you will have a graphics context - a bezier path is useless without one. When you do, set its path to your bezier path, set its stroke / fill color as desired, and then stroke / fill the path. Voilà.
In your case, you seem to have a pair of CAShapeLayer objects. You can change their stroke / fill colors, because they have a graphics context - they take the path and colors you give them, and draw them for you by filling and stroking the path. Fine. But you cannot change a bezier path's stroke or fill color - it's just a path. The entire notion is meaningless.
Having said all that, it is far from clear what issue you are having. Based on your code, I ran this bit of it:
class ViewController: UIViewController {
@IBOutlet weak var outerCircleView: UIView!
override func viewDidLoad() {
super.viewDidLoad()
let outerCircle = CAShapeLayer()
let frameSize = outerCircleView.frame.size
outerCircle.path = UIBezierPath(ovalInRect: CGRect(x: 0.0, y: 0.0, width: frameSize.width, height: frameSize.height)).CGPath
outerCircle.lineWidth = 8.0
outerCircle.strokeStart = 0.0
outerCircle.strokeEnd = 0.45
outerCircle.lineCap = kCALineCapRound
outerCircle.fillColor = UIColor.clearColor().CGColor
outerCircle.strokeColor = UIColor.grayColor().CGColor
outerCircleView.layer.addSublayer(outerCircle)
}
}
It builds and runs, and I see exactly what I would expect to see: a thick gray part-circle:
That is because this shape layer has a clear fill color and a grey stroke color. If you don't like those colors, ask the shape layer to give you different colors.
UPDATE You updated your code to show a second version involving green fill and stroke. So I tried your second code:
override func viewDidLoad() {
super.viewDidLoad()
// Do any additional setup after loading the view, typically from a nib.
let outerCircle = CAShapeLayer()
let frameSize = outerCircleView.frame.size
outerCircle.path = UIBezierPath(ovalInRect: CGRect(x: 0.0, y: 0.0, width: frameSize.width, height: frameSize.height)).CGPath
outerCircle.lineWidth = 8.0
outerCircle.strokeStart = 0.0
outerCircle.strokeEnd = 0.45
outerCircle.lineCap = kCALineCapRound
outerCircle.fillColor = UIColor.greenColor().CGColor
outerCircle.strokeColor = UIColor.greenColor().CGColor
outerCircleView.layer.addSublayer(outerCircle)
outerCircle.strokeStart = 0.0
outerCircle.strokeEnd = 1.0
}
And, as expected, I got a green circle (it isn't an exact circle, but that is just because my view is not a perfect square):
So again I don't see what the problem is supposed to be: your code does just what I would expect your code to do.
来源：https://stackoverflow.com/questions/29503627/how-can-i-change-the-color-of-an-element-using-a-uibezierpath