ios - 未能对 UIBezierPath 进行描边()

Question

我希望创建一个完美的圆形矩形(圆形)并将其绘制在屏幕上。我已经在 Playground 上测试了我的代码，它成功地绘制了 UIBezierPath。然而，它并没有在 iOS 模拟器中成功绘制它。这是我一直在处理的代码:

    class Circles {

        //Defining the rounded rect (Circle)
        func roundRect(radius: CGFloat, angle: CGFloat) -> UIBezierPath {

            //Creating the rounded the rectangle (Circle)
            var roundedRect = UIBezierPath()
            roundedRect.addArcWithCenter(CGPointZero, radius: radius,
                startAngle: 0, endAngle: angle ,
                clockwise: true)

            return roundedRect
        }


        //Drawing the Bezier Path (Circle)
        func drawRect(rect: UIBezierPath){

            rect.moveToPoint(self.point)
            UIColor.blackColor().setStroke()
            rect.stroke()
        }

        //Giving the rounded rect (Circle) it's position
        var point = CGPointMake(500, 500)
    }
    //Giving the rounded rect (Circle) it's size
    var newRect = Circles().roundRect(200.0, angle: 7)

    //Drawing the rounded rect (Circle)
    Circles().drawRect(newRect)

几年前我看过其他一些有类似问题的帖子，但是它们是在 Objective-C 中，我尝试翻译但没有任何用处。我还尝试了其他几种在屏幕上绘制路径的方法，但遗憾的是，它没有用。我对它进行了测试以确保函数与 println 语句一起使用，问题是我不知道为什么笔画没有激活。感谢阅读，-Zach。

这是使用 Mike 所说的更新版本:

class CircleView: UIView {
override func drawRect(rect: CGRect) {

    // Creating the rectangle's size
    var newRect = Circles().roundRect(200.0, angle: 7)

    //Drawing the rectangle
    Circles().drawRect(newRect)
}


//Holding all to do with the circle
class Circles {

    //Defining the rounded rect (Circle)
    func roundRect(radius: CGFloat, angle: CGFloat) -> UIBezierPath {

        //Creating the rounded rect (Circle)
        var roundedRect = UIBezierPath()
        roundedRect.addArcWithCenter(CGPointZero, radius: radius,
            startAngle: 0, endAngle: angle ,
            clockwise: true)

        return roundedRect
    }


    //Drawing the Bezier Path (Circle)
    func drawRect(rect: UIBezierPath){

        rect.moveToPoint(self.point)
        UIColor.blackColor().setStroke()
        UIColor.blackColor().setFill()
        rect.stroke()
        rect.fill()
    }

    //Giving the rounded rect (Circle) it's position
    var point = CGPointMake(500, 500)
    }

}



class ViewController: UIViewController {



override func viewDidLoad() {
super.viewDidLoad()
    // Do any additional setup after loading the view, typically from a nib.

    //Generating the background
    self.view.backgroundColor = UIColor(patternImage: UIImage(named: "normalpaper.jpg"))

    let circleView = CircleView(frame: self.view.bounds)
    self.view.addSubview(circleView)

}

Answer 1

正如您在评论中提到的，您正在从 UIViewController 的 viewDidLoad 函数中调用 drawRect。您那里没有有效的绘图上下文，所以这不会起作用。

最简单的方法是创建一个 UIView 子类，它有自己的 drawRect 函数，调用 Circle().drawRect(...) 并将其添加为 UIViewController 的 view 的 subview 。

这是一个例子:

注意:我通过设置 circleView.opaque = false 使自定义 View 透明，这样您在评论中提到的背景就会显示出来。

class CircleView: UIView {
    override func drawRect(rect: CGRect) {
        // I just copied this directly from the original question
        var newRect = Circles().roundRect(200.0, angle: 7)
        Circles().drawRect(newRect)
    }
}

class ViewController: UIViewController {
    override func viewDidLoad() {
        super.viewDidLoad()

        // Create a new CircleView that's the same size of this 
        // view controller's bounds and add it to the view hierarchy
        let circleView = CircleView(frame: self.view.bounds)
        circleView.opaque = false
        self.view.addSubview(circleView)
    }
}

注意:如果您要进行自定义绘图，我强烈建议您阅读 Drawing and Printing Guide for iOS .它会教您让它发挥作用所需的所有基础知识。