Swift 函数不更新绘图

Question

我的 View Controller 中有一个步进器，可以更新变量(redd1，greenn1，bluee1)。我有一个通过重写 drawRect 函数绘制的圆。函数 updateColor() 假设用变量中更新的颜色绘制一个新的圆。当我打印变量的新值时，它们显示正确，但圆圈的颜色仍然没有改变。

 func updateColor()
{
    let circle = UIView(frame: CGRect(x: -25.0, y: 10.0, width: 100.0,    height: 100.0))
    circle.layer.cornerRadius = 50.0;
    let startingColor = UIColor(red: (CGFloat(redd1))/255, green: (CGFloat(greenn1))/255, blue: (CGFloat(bluee1))/255, alpha: 1.0)
    circle.backgroundColor = startingColor;
    addSubview(circle);
    //print(redd1);
}

Answer 1

每次您想要更改颜色时，您都会创建并添加一个新圆圈(UIView)。为什么不简单地改变现有圆圈的颜色呢？

class Foo: UIView {

    var red: Float = 255
    var green: Float = 0
    var blue: Float = 0

    private let circle = UIView(frame: CGRect(x: -25.0, y: 10.0, width: 100.0, height: 100.0))

    private var circleColor: UIColor {
        return UIColor(
            red: (CGFloat(self.red))/255,
            green: (CGFloat(green))/255,
            blue: (CGFloat(blue))/255,
            alpha: 1.0)
    }

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

    required init(coder aDecoder: NSCoder) {
        fatalError("This class does not support NSCoding")
    }

    private func addCircle() {
        circle.layer.cornerRadius = 50.0
        circle.backgroundColor = self.circleColor
        addSubview(circle)
    }

    func updateColor() {
        circle.backgroundColor = self.circleColor
    }
}