How do I draw a circle in iOS Swift

Question

let block   UIView frame  CGRectMake cellWidth-25  cellHeight 2-8  16  16   block backgroundColor   UIColor netHex  0xff3b30  block layer cornerRadius   9 block clipsToBounds   true   This is what I have right now  but it s obviously not the right way to do it   What s the simplest way to do it

User · Answer

A much easier and resource friendly approach would be.

import UIKit

@IBDesignable
class CircleDrawView: UIView {

    @IBInspectable var borderColor: UIColor = UIColor.red;

    @IBInspectable var borderSize: CGFloat = 4

    override func draw(_ rect: CGRect)
    {
        layer.borderColor = borderColor.cgColor
        layer.borderWidth = borderSize
        layer.cornerRadius = self.frame.height/2
    }

}

With Border Color and Border Size and the default Background property you can define the appearance of the circle.

Please note, to draw a circle the view's height and width have to be equal in size.

The code is working for Swift >= 4 and Xcode >= 9.

User · Answer

A simple function drawing a circle on the middle of your window frame  using a multiplicator percentage      CGFloat is a multiplicator from self view frame width func drawCircle withMultiplicator coefficient  CGFloat         let radius   self view frame width   2   coefficient      let circlePath   UIBezierPath arcCenter  self view center  radius  radius  startAngle  CGFloat 0   endAngle CGFloat Double pi   2   clockwise  true      let shapeLayer   CAShapeLayer       shapeLayer path   circlePath cgPath        change the fill color     shapeLayer fillColor   UIColor clear cgColor     shapeLayer strokeColor   UIColor darkGray cgColor     shapeLayer lineWidth   2 0      view layer addSublayer shapeLayer

User · Answer

If you want to use a UIView to draw it  then you need to make the radius   of the height or width   so just change   block layer cornerRadius   9   to   block layer cornerRadius   block frame width   2   You ll need to make the height and width the same however  If you d like to use coregraphics  then you ll want to do something like this   CGContextRef ctx  UIGraphicsGetCurrentContext    CGRect bounds    self bounds    CGPoint center  center x   bounds origin x   bounds size width   2 0  center y   bounds origin y   bounds size height   2 0  CGContextSaveGState ctx    CGContextSetLineWidth ctx 5   CGContextSetRGBStrokeColor ctx 0 8 0 8 0 8 1 0   CGContextAddArc ctx locationOfTouch x locationOfTouch y 30 0 0 M PI 2 YES   CGContextStrokePath ctx

User · Answer

Make a class UIView and assign it this code for a simple circle  import UIKit  IBDesignable class DRAW  UIView        override func draw   rect  CGRect             var path   UIBezierPath           path   UIBezierPath ovalIn  CGRect x  50  y  50  width  100  height  100           UIColor yellow setStroke           UIColor red setFill           path lineWidth   5         path stroke           path fill

User · Answer

Add in view did load        Circle Points       var CircleLayer     CAShapeLayer         let center   CGPoint  x  myCircleView frame size width   2  y  myCircleView frame size height   2      let circleRadius   myCircleView frame size width   2     let circlePath   UIBezierPath arcCenter  center  radius  circleRadius  startAngle  CGFloat M PI   endAngle  CGFloat M PI   4   clockwise  true      CircleLayer path   circlePath cgPath    CircleLayer strokeColor   UIColor red cgColor     CircleLayer fillColor   UIColor blue cgColor     CircleLayer lineWidth   8     CircleLayer strokeStart   0     CircleLayer strokeEnd    1     Self View layer addSublayer CircleLayer

User · Answer

I find Core Graphics to be pretty simple for Swift 3   if let cgcontext   UIGraphicsGetCurrentContext         cgcontext strokeEllipse in  CGRect x  center x-diameter 2  y  center y-diameter 2  width  diameter  height  diameter

User · Answer

Updating  Dario s code approach for Xcode 8 2 2  Swift 3 x   Noting that in storyboard  set the Background color to  clear  to avoid a black background in the square UIView   import UIKit  IBDesignable class Dot UIView        IBInspectable var mainColor  UIColor   UIColor clear                   didSet   print  mainColor was set here                IBInspectable var ringColor  UIColor   UIColor clear                   didSet   print  bColor was set here                IBInspectable var ringThickness  CGFloat   4                   didSet   print  ringThickness was set here                  IBInspectable var isSelected  Bool   true      override func draw   rect  CGRect                 let dotPath   UIBezierPath ovalIn  rect          let shapeLayer   CAShapeLayer           shapeLayer path   dotPath cgPath         shapeLayer fillColor   mainColor cgColor         layer addSublayer shapeLayer           if  isSelected    drawRingFittingInsideView rect  rect               internal func drawRingFittingInsideView rect  CGRect - gt                  let hw CGFloat   ringThickness 2         let circlePath   UIBezierPath ovalIn  rect insetBy dx  hw dy  hw             let shapeLayer   CAShapeLayer           shapeLayer path   circlePath cgPath         shapeLayer fillColor   UIColor clear cgColor         shapeLayer strokeColor   ringColor cgColor         shapeLayer lineWidth   ringThickness         layer addSublayer shapeLayer            And if you want to control the start and end angles   import UIKit  IBDesignable class Dot UIView        IBInspectable var mainColor  UIColor   UIColor clear                   didSet   print  mainColor was set here                IBInspectable var ringColor  UIColor   UIColor clear                   didSet   print  bColor was set here                IBInspectable var ringThickness  CGFloat   4                   didSet   print  ringThickness was set here                  IBInspectable var isSelected  Bool   true      override func draw   rect  CGRect                 let dotPath   UIBezierPath ovalIn  rect          let shapeLayer   CAShapeLayer           shapeLayer path   dotPath cgPath         shapeLayer fillColor   mainColor cgColor         layer addSublayer shapeLayer           if  isSelected    drawRingFittingInsideView rect  rect               internal func drawRingFittingInsideView rect  CGRect - gt                  let halfSize CGFloat   min  bounds size width 2  bounds size height 2          let desiredLineWidth CGFloat   ringThickness      your desired value          let circlePath   UIBezierPath              arcCenter  CGPoint x  halfSize  y  halfSize               radius  CGFloat  halfSize -  desiredLineWidth 2                 startAngle  CGFloat 0               endAngle CGFloat Double pi               clockwise  true           let shapeLayer   CAShapeLayer           shapeLayer path   circlePath cgPath         shapeLayer fillColor   UIColor clear cgColor         shapeLayer strokeColor   ringColor cgColor         shapeLayer lineWidth   ringThickness         layer addSublayer shapeLayer

User · Answer

Swift 4 version of accepted answer    IBDesignable class CircledDotView  UIView         IBInspectable var mainColor  UIColor    white           didSet   print  mainColor was set here                IBInspectable var ringColor  UIColor    black           didSet   print  bColor was set here                IBInspectable var ringThickness  CGFloat   4           didSet   print  ringThickness was set here                 IBInspectable var isSelected  Bool   true      override func draw   rect  CGRect            let dotPath   UIBezierPath ovalIn  rect          let shapeLayer   CAShapeLayer           shapeLayer path   dotPath cgPath         shapeLayer fillColor   mainColor cgColor         layer addSublayer shapeLayer           if  isSelected                drawRingFittingInsideView rect  rect                       internal func drawRingFittingInsideView rect  CGRect            let hw  CGFloat   ringThickness   2         let circlePath   UIBezierPath ovalIn  rect insetBy dx  hw  dy  hw            let shapeLayer   CAShapeLayer           shapeLayer path   circlePath cgPath         shapeLayer fillColor   UIColor clear cgColor         shapeLayer strokeColor   ringColor cgColor         shapeLayer lineWidth   ringThickness         layer addSublayer shapeLayer

User · Answer

Here is my version using Swift 5 and Core Graphics   I have created a class to draw two circles  The first circle is created using addEllipse    It puts the ellipse into a square  thus creating a circle  I find it surprising that there is no function addCircle    The second circle is created using addArc   of 2pi radians   import UIKit   IBDesignable class DrawCircles  UIView        override init frame  CGRect            super init frame  frame             required public init  coder aDecoder  NSCoder            super init coder  aDecoder             override func draw   rect  CGRect             guard let context   UIGraphicsGetCurrentContext   else               print  could not get graphics context               return                    context setLineWidth 2           context setStrokeColor UIColor blue cgColor           context addEllipse in  CGRect x  30  y  30  width  50 0  height  50 0            context strokePath            context setStrokeColor UIColor red cgColor           context beginPath      this prevents a straight line being drawn from the current point to the arc          context addArc center  CGPoint x 100  y  100   radius  20  startAngle  0  endAngle  2 0 CGFloat pi  clockwise  false           context strokePath             in your ViewController s didViewLoad   add the following   let myView   DrawCircles frame  CGRect x  50  y  50  width  300  height  300    self view addSubview myView    When it runs it should look like this  I hope you like my solution

User · Answer

WARNING  This is an incorrect solution  layers are added infinitely in the drawRect method  every time the view is drawn   You should NEVER add layers in the drawRect method  Use layoutSubview instead   You can draw a circle with this  Swift 3 0    let circlePath   UIBezierPath arcCenter  CGPoint x  100  y  100   radius  CGFloat 20   startAngle  CGFloat 0   endAngle  CGFloat Double pi   2   clockwise  true       let shapeLayer   CAShapeLayer   shapeLayer path   circlePath cgPath         Change the fill color shapeLayer fillColor   UIColor clear cgColor    You can change the stroke color shapeLayer strokeColor   UIColor red cgColor    You can change the line width shapeLayer lineWidth   3 0      view layer addSublayer shapeLayer   With the code you have posted you are cropping the corners of the UIView  not adding a circle to the view   Here s a full example of using that method      A special UIView displayed as a ring of color class Ring  UIView       override func drawRect rect  CGRect            drawRingFittingInsideView                  internal func drawRingFittingInsideView   - gt               let halfSize CGFloat   min  bounds size width 2  bounds size height 2          let desiredLineWidth CGFloat   1    your desired value                      let circlePath   UIBezierPath                  arcCenter  CGPoint x halfSize y halfSize                   radius  CGFloat  halfSize -  desiredLineWidth 2                     startAngle  CGFloat 0                   endAngle CGFloat M PI   2                   clockwise  true                let shapeLayer   CAShapeLayer            shapeLayer path   circlePath CGPath                       shapeLayer fillColor   UIColor clearColor   CGColor          shapeLayer strokeColor   UIColor redColor   CGColor          shapeLayer lineWidth   desiredLineWidth               layer addSublayer shapeLayer              Note  however there s an incredibly handy call  let circlePath   UIBezierPath ovalInRect  rect  which does all the work of making the path   Don t forget to inset it for the line thickness  which is also incredibly easy with CGRectInset   internal func drawRingFittingInsideView rect  CGRect        let desiredLineWidth CGFloat   4       Your desired value     let hw CGFloat   desiredLineWidth 2          let circlePath   UIBezierPath ovalInRect  CGRectInset rect hw hw       let shapeLayer   CAShapeLayer       shapeLayer path   circlePath CGPath     shapeLayer fillColor   UIColor clearColor   CGColor     shapeLayer strokeColor   UIColor redColor   CGColor     shapeLayer lineWidth   desiredLineWidth     layer addSublayer shapeLayer       In practice these days in Swift  you would certainly use  IBDesignable and  IBInspectable  Using these you can actually see and change the rendering  in Storyboard  As you can see  it actually adds new features to the Inspector on the Storyboard  which you can change on the Storyboard       A dot with a border  which you can control completely in Storyboard  IBDesignable class Dot  UIView         IBInspectable var mainColor  UIColor   UIColor blueColor             didSet                 print  quot mainColor was set here quot                         IBInspectable var ringColor  UIColor   UIColor orangeColor              didSet                print  quot bColor was set here quot                          IBInspectable var ringThickness  CGFloat   4           didSet                print  quot ringThickness was set here quot                             IBInspectable var isSelected  Bool   true          override func drawRect rect  CGRect            let dotPath   UIBezierPath ovalInRect rect          let shapeLayer   CAShapeLayer           shapeLayer path   dotPath CGPath         shapeLayer fillColor   mainColor CGColor         layer addSublayer shapeLayer                   if  isSelected                 drawRingFittingInsideView rect                           internal func drawRingFittingInsideView rect  CGRect            let hw CGFloat   ringThickness 2         let circlePath   UIBezierPath ovalInRect  CGRectInset rect hw hw                     let shapeLayer   CAShapeLayer           shapeLayer path   circlePath CGPath         shapeLayer fillColor   UIColor clearColor   CGColor         shapeLayer strokeColor   ringColor CGColor         shapeLayer lineWidth   ringThickness         layer addSublayer shapeLayer            Finally  note that if you have a UIView  which is square  and which you set to say red in Storyboard  and you simply want to turn it in to a red circle  you can just do the following     Makes a UIView into a circular dot of color class Dot  UIView       override func layoutSubviews             layer cornerRadius   bounds size width 2

[ios] How do I draw a circle in iOS Swift?

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