how to draw a semi-circle using swift IO9 and on t

问题:

I want to draw the two semi circles like this as shown in picture (the below one)

I m trying it from few days but did not get anything Tried some chart api and a few code to draw pie chart from stackoverflow but they need to edit and i dont know about Core Grahpics as i am new to this I AM Working on xcode 7.3.1 and IOS 9 MY Question is : - how to draw a semi-circle which take one value and first convert that value to get its equivalent angle and then draw an arc of this angle and fill color in that part Or provide me some link with the help of which i can learn draw them on my own Thanks

回答1:

The below code runs in the XCode iOS Playground. It creates a custom UIView class and draws two pie slices. The start and end angle are specified in percent of a full circle.

You can easily extend it to display more or less slices depending on the data you have.

The drawRect method creates a bezier path that starts in the center, then adds an arc segment and finally closes the path so it can be filled.

import UIKit

class PieChart : UIView {

    override func drawRect(rect: CGRect) {

        drawSlice(rect, startPercent: 0, endPercent: 50, color: UIColor.greenColor())
        drawSlice(rect, startPercent: 50, endPercent: 75, color: UIColor.redColor())
    }

    private func drawSlice(rect: CGRect, startPercent: CGFloat, endPercent: CGFloat, color: UIColor) {
        let center = CGPoint(x: rect.origin.x + rect.width / 2, y: rect.origin.y + rect.height / 2)
        let radius = min(rect.width, rect.height) / 2
        let startAngle = startPercent / 100 * CGFloat(M_PI) * 2 - CGFloat(M_PI)
        let endAngle = endPercent / 100 * CGFloat(M_PI) * 2 - CGFloat(M_PI)
        let path = UIBezierPath()
        path.moveToPoint(center)
        path.addArcWithCenter(center, radius: radius, startAngle: startAngle, endAngle: endAngle, clockwise: true)
        path.closePath()
        color.setFill()
        path.fill()
    }
}

let pieChart = PieChart(frame: CGRect(x: 0.0, y: 0.0, width: 300.0, height: 300.0))
pieChart.backgroundColor = UIColor.clearColor()

回答2:

My issue has been resolved.

We just need to do a little change in the first line to make it like as in picture's semicircle:

drawSlice(rect, startPercent: 0, endPercent: 50, color: UIColor.greenColor())
drawSlice(rect, startPercent: 0, endPercent: 25, color: UIColor.redColor())

回答3:

Codo's code in Swift 3:

import UIKit

class PieChart : UIView {

    override func draw(_ rect: CGRect) {

        drawSlice(rect, startPercent: 0, endPercent: 50, color: .green)
        drawSlice(rect, startPercent: 50, endPercent: 75, color: .red)
    }

    private func drawSlice(_ rect: CGRect, startPercent: CGFloat, endPercent: CGFloat, color: UIColor) {
        let center = CGPoint(x: rect.origin.x + rect.width / 2, y: rect.origin.y + rect.height / 2)
        let radius = min(rect.width, rect.height) / 2
        let startAngle = startPercent / 100 * CGFloat.pi * 2 - CGFloat.pi
        let endAngle = endPercent / 100 * CGFloat.pi * 2 - CGFloat.pi
        let path = UIBezierPath()
        path.move(to: center)
        path.addArc(withCenter: center, radius: radius, startAngle: startAngle, endAngle: endAngle, clockwise: true)
        path.close()
        color.setFill()
        path.fill()
    }
}

let pieChart = PieChart(frame: CGRect(x: 0.0, y: 0.0, width: 300.0, height: 300.0))
pieChart.backgroundColor = UIColor.clear