Swift: 围绕标签画一个圆

Question

我试图在运行时在 TableViewCell 的单元格中围绕标签绘制一个圆圈。

我可以弄清楚如何使它大致围绕标签，但我在将它准确地围绕标签居中时遇到了一些问题。

圆圈似乎在标签的右侧和中间绘制。

到目前为止，这是我的代码，我相信这对其他人来说很容易。

func drawCircle() {
    let x = countLabel.layer.position.x - (countLabel.frame.width)
    let y = countLabel.layer.position.y - (countLabel.frame.height / 2)
    let circlePath = UIBezierPath(roundedRect: CGRectMake(x, y, countLabel.frame.height, countLabel.frame.height), cornerRadius: countLabel.frame.height / 2).CGPath

    let circleShape = CAShapeLayer()
    circleShape.path = circlePath
    circleShape.lineWidth = 3
    circleShape.strokeColor = UIColor.whiteColor().CGColor
    circleShape.fillColor = UIColor.clearColor().CGColor

    self.layer.addSublayer(circleShape)
}

Answer 1

呃，这就是我的想法，愚蠢的错误。

在处理贝塞尔路径时，X 和 Y 是从中间计算的，而不是从左上角计算的。

所以 x 和 y 的代码应该如下：

let x = countLabel.layer.position.x - (countLabel.frame.height / 2)
let y = countLabel.layer.position.y - (countLabel.frame.height / 2)

Answer 2

试试这个：

func drawCircle() {
    var padding : CGFloat = 8

    let x = countLabel.layer.position.x - (countLabel.frame.width / 2)
    let y = countLabel.layer.position.y  - (countLabel.frame.width / 2)
    let circlePath = UIBezierPath(roundedRect: CGRectMake(x - padding, y - padding, countLabel.frame.width + (2 * padding), countLabel.frame.width + (2 * padding)), cornerRadius: (countLabel.frame.width + (2 * padding)) / 2).CGPath

    let circleShape = CAShapeLayer()
    circleShape.path = circlePath
    circleShape.lineWidth = 3
    circleShape.strokeColor = UIColor.greenColor().CGColor
    circleShape.fillColor = UIColor.clearColor().CGColor

    self.view.layer.addSublayer(circleShape)
}

修改填充变量以调整标签和圆之间的填充。干杯！

Answer 3

您可以只在标签图层上使用圆角半径。您将标签制作成正方形，然后将其层的角半径设置为标签 width/height 的一半，这将使它成为完美的圆形。您将边框宽度设置为大于零的值，将边框颜色设置为您要使用的笔触颜色。

let size:CGFloat = 35.0 // 35.0 chosen arbitrarily

countLabel.bounds = CGRectMake(0.0, 0.0, size, size) 
countLabel.layer.cornerRadius = size / 2
countLabel.layer.borderWidth = 3.0
countLabel.layer.backgroundColor = UIColor.clearColor().CGColor
countLabel.layer.borderColor = UIColor.greenColor().CGColor

它将看起来像这样：

虽然完整的代码在单个视图控制器中是这样的 iPad 模板项目：

import UIKit

class ViewController: UIViewController {

    override func viewDidLoad() {
        super.viewDidLoad()

        let size:CGFloat = 35.0 // 35.0 chosen arbitrarily

        let countLabel = UILabel()
        countLabel.text = "5"
        countLabel.textColor = .greenColor()
        countLabel.textAlignment = .Center
        countLabel.font = UIFont.systemFontOfSize(14.0)
        countLabel.bounds = CGRectMake(0.0, 0.0, size, size)
        countLabel.layer.cornerRadius = size / 2
        countLabel.layer.borderWidth = 3.0
        countLabel.layer.backgroundColor = UIColor.clearColor().CGColor
        countLabel.layer.borderColor = UIColor.greenColor().CGColor

        countLabel.center = CGPointMake(200.0, 200.0)

        self.view.addSubview(countLabel)
    }

}

Answer 4

countLabel.layer.cornerRadius = 0.5 * countLabel.bounds.size.width

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