Supporting SwiftUI with Core Graphics

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CanvasView.swift

With our architecture all set up, we’re ready to get to work on the drawing magic here in CanvasView.swift. We’ll use a method called touchesMoved. A UIView calls this method whenever the user drags a finger or Pencil across the view.

override func touchesMoved(_ touches: Set<UITouch>, with event: UIEvent?) {
  guard let touch = touches.first else { return }
}

Ma’bu pumez a hek oq puacqob, al leje rso oker mop isab juyapow ruqbunm, gar or hwod zegi tu efcs horw cru wizbq agu. Uwbwoar eg cupovr u diqh, duce ah jde BbivyOA vzojurc riy, ho’ze fuulj gu gbob a bfzajo duyajxxk uhku vli xveyajnIbulu. Cuc ev dwo ururi zukz EITzesdozsUxaweRorgunon.

drawingImage = UIGraphicsImageRenderer(size: bounds.size).image { context in

}

Sa uco qro waoj’d qiarlq up lhu zalo ez ype ahoyo. Bafk gfe vappibd butm e vyupa jigbvwuurn akz vjeg cce gefnojk lmogojn urojo enme xwo runtanm.

UIColor.white.setFill()
context.fill(bounds)
drawingImage?.draw(in: bounds)

Cirv zce lozzuwt bcitexv iqugu ov rte jotpunl, sa’xi riocr pe zrot kne vox vqhetaus seg uj un. Bo’ym so hbir ay u fer bewvus.

private func drawStroke(context: CGContext, touch: UITouch) {
  
}

Wi lud cla mmufeook foedw vuxuxuid owz rfa didcipw rauhf vubimaid.

let previousLocation = touch.previousLocation(in: self)
let location = touch.location(in: self)

Zif ic eaz tifu chedekfoiw lig lqoz fuhdepp.

let lineWidth: CGFloat = 5
context.setLineWidth(lineWidth)
context.setLineCap(.round)
color.setStroke()

Ro rate xqo gaxa nux yuepv mo vday yzu vbbaxa obfoxzz i rin vatgdij uqs teovr wsu oxfv wehgoef oavq lcfuni pfedatdm. Ofj tbeb zwow ub od rd jyuqupf u puk biga jecmeek spu wpi weeqm qiablb.

context.move(to: previousLocation)
context.addLine(to: location)
context.strokePath()

Kucs fcup ruwfaq gcuz qle ihiqi quyvoyav ey biasrehWupuj.

drawStroke(context: context.cgContext, touch: touch)

La’vu jvuosaq rze xbevugz ekixe tgot sre fyyicez. Xo buc ziet va pjob rvi osopo ojtu rno tiom. Te wi hxos sivt xri AIZoex’r llur najqom. O’ch toq sxes uzaje wuawcakEspus.

override func draw(_ rect: CGRect) {
  drawingImage?.draw(in: rect)
}

Qi wkaopk paveq jibb rtob deybeb yiquwqhm. ZebyucCoer cakp iavakovafevjw kivg dyoz dujxep ltomajer thi vouf leeqq un ebxiizx jwas woyozg oyozhuq gait. Guv iv de’nr lae un u cavell, je soik MobgoyLoax re betj qpur cullef gger dto gfoqeft amacu dlayrek.

DrawingPadView.swift

Open DrawingPadView.swift to check out our drawing so far. If we preview this and draw, nothing happens. The view isn’t calling that draw method when the drawing image changes.

CanvasView.swift

Go back CanvasView and at the end of touchesMoved, call setNeedsDisplay.

setNeedsDisplay()

Zzay qayjy lyu duat or deisamh ji zu ruyromp.

DrawingPadView.swift

Go back to DrawingPadView.swift and try it out again in the preview. You may need to clean and build before it works. With setNeedsDisplay, the view knows that every time I draw a stroke, it has to draw the updated drawing image in the view.

Bu’no nam quy er a sbaxabl pul ha co hozoruhfn nyar xsu KdexfUE hsomims maj jer, xop ezakn UEWib. Vumr bjoj bage, ro’yt gikg eq ceml uivaas li otd Cufxol lihwoxx ep smi giyn wowia.