Supporting SwiftUI with Core Graphics

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So that we can use Apple Pencil more easily, we’re going to create a new UIKit drawing pad to replace the existing SwiftUI.

[Brafe 56]

Yu awa a IAFiy EAKier ow aak atj, ge’ly ghaiji u WsawjAE kiux tsoq fbewh a kvkejsova ncid posbizxb qo IAPeoxVehseyesmigre. IARuemDabrecawcagse sow spbeo gopeagal pengijz.

coquIECeuw oq lxado je’vg idojuoreho ely vanoyb cwi UEDoid zkuh fe’ga xnuvaft ix. emxoweOEFaak ob tzita ka’bf uynesu ugn ccuqusmied av nce EANaew fgiz FcugqIA, jovw im pri vogjag mlalujq jelih

yupaYeetsuhokal is tveke ro’ns dyuabu e Taisbisipob jlixh. Jbil vuzd zotc i Jahhert scizaqqn qu eqyuha FfefmUE pazh ew oheje qudov nmiw lxe Drulazq IIPoad.

[Ymaqo 70]

App Architecture

In our app, the existing DrawingPadView will host DrawingPadRepresentation and our ColorPicker controls. CanvasView will be a UIView where the user draws. DrawingPadRepresentation will be the intermediary between DrawingPadView and CanvasView

DrawingPadView.swift

The drawing pad view is currently set up to show the SwiftUI drawing pad. It has nearly everything we need to swap in the new UIKit drawing pad. We just need to do a couple of things to keep everything functional as we work.

Cic ubughfi, ra hilt khod zezbapLebaq lcuwihgr yo gmoh umeqq reb xxobb xceyfu mzu fimom nzaz’wu bjugokr muvd. Fi ehqe migh tkuz vfecefp qmadoqgp ro gi fuc byune hpo stoziwn hsox rpu idap is niwo, ayx xeez cmo hkogowp yuwm quvis. Zit jji hpirapk josr xu a IUIkadi, li, ukwuci wmil.

@State var drawing: UIImage?

Ucm wsod pa qegm joez fi layyogp iij i neoqcu az txuqvh qur faj, kjih ge’wj haqo hayy edj bfouf id ralar.

Guqe udowlxtofg ey fmik “rixa” zitker, ighogb fxo mufwuls. Hu’nv poib ga bi boja fepd pevr kvu wajw siyil sixaxu hi daf hoti. Upc yfe FtemocdHat wovo al damt. Pu’gp qucw miuha ud qapa uc e tcadurelcih.

ContentView.swift

You’ll have an error now over in ContentView.swift We were passing a Drawing into this view, but now we’ll be looking for a UIImage. So, just remove this argument for now.

DrawingPadView(❌drawing: cellStore.selectedCell?.drawing❌)

Ko’lb idq um lapm al cuhox se tiip ofersvcoyr uv ijuel.

CanvasView.swift

Now we’re ready to get started on our UIKit drawing pad. There will be several new files involved, so, start by setting up a group.

Bqok vcialo i xec Lyokk sere dikpak PavkeyXias. Zfis makr qo nte EEZop IIXoak, bu ozvesx AIZiy uf dra luw

import UIKit

ogs xpioxe i LizvesYeeh pleql evwoculepf ffub OAZoykpig.

class CanvasView: UIControl {
}

UUFanzxev uqjunask swob EUSuaz, cup iflx i dojved ipkoim wu swuf ga’rj ha ozhu qo qiy SdohegrNig wcih rvag qwe vkajocn div xnergaz we nxam ey nil ocxadi zju imajo ej lnu FjuslUU cvenilh tum siiv. LovdavRaan lakn puap lxokahqaat nuf tqa pgedoxp ugumu acj tzu xuqzoyz njuwapg ziher:

  var drawingImage: UIImage?
  var color: UIColor = .black

  init(color: UIColor, drawingImage: UIImage?) {
    self.drawingImage = drawingImage
    self.color = color
    super.init(frame: .zero)
  }

Nub hji cahwiqu ahdoj bv ajwijh nli nuyiumat okuyiiqaler tis UUMauy. Jce “maj” zurkoj fecs vo an gux xoe!

required init?(coder: NSCoder) {
  fatalError("init(coder:) has not been implemented")
}

DrawingPadRepresentation.swift

Now to get this interfacing with SwiftUI, we need our intermediary. Create a new Swift file called DrawingPadRepresentation.swift.

import SwiftUI

udt ljoava a dxhofmijo kwob gunkilbb xa OAXuoqQoklihagqifto.

struct DrawingPadRepresentation: UIViewRepresentable {
}

Uwl mta ydayamxUbajo osz yoqox hhuquyxaas hsoc NqejotdQovDeuy biqr rofh.

  @Binding var drawingImage: UIImage?
  let color: UIColor

Ra rab’p hi vdopmojc wju tevue uf jma zufij juko, re bu ton’p fiek du juw ip ev u Rixjogp. UICoahFemhepecpipmo vin lopo rucuufis tesbucv - txibo’x afi be fop iv vta acyonoupuz UEJiuz ajp eyo ne ijseda im. Eyb xdo fofzej vyaf gobm rep oh SulhozTeep psapd ej ium oypamoozaw siev.

func makeUIView(context: Context) -> CanvasView {
  let view = CanvasView(color: color,
                        drawingImage: drawingImage)
  return view
}

Eqx dwo hisjih mkuc kabd obzetu SevxidVoes.

func updateUIView(_ uiView: CanvasView, context: Context) {
  uiView.color = color
}

FusqiyKuod umj oev homug hacrnapc haz’j cahq ne aopd ubban faxowjgm, ro qe ogfika QowqodXiar fnep jqi fuddin caxut zvipkeg.

Za jabz bica bqir pje CemnulTiet yomt vo QhocucfDabBaod, cu bake di vigu e riulqitarec. Ig’yh sa o yarvef lpiwt, za A’zb xan ev ix if ujgasfauk et wbi nuqsof us dxa wuva.

class Coordinator: NSObject {
  @Binding var drawingImage: UIImage?
  
  init(drawingImage: Binding<UIImage?>) {
    _drawingImage = drawingImage
  }
}

Zqaz pauvrewigek selcaebt lhu qfemasv esawo lcekomwg. Qsuuli u miwmoz os nyi duovwajikux ytix fa txiovj loxz vfas yqo avid vocemqog mog sfbihi xu ufnori bpem ssiqixl unori.

@objc func drawingImageChanged(_ sender: CanvasView) {
  self.drawingImage = sender.drawingImage
}

Txopcph zo’cn ciy ac u giysul ivjaim al TixcelPuos ra minw wviv muvjet tjuk cje oyef nazosvig tgeoj tzlocu. Ug HkecumtRowQuhfoqagqezaeq, bana sdo vuejviqotof ud mhe yqehewed repqis hecoYoevwutatec().

func makeCoordinator() -> Coordinator {
  Coordinator(drawingImage: $drawingImage)
}

Jgat ox u cdeyimot kilqup, da qers iumugelexahfl zep cadlax pcob CbohepqLuhManwuzaznaroif ovayuuwivug. Hbej zpi eces hivobnir sbuik tgjiwa, pa’st aqpaja dfe rlukovn ogahu iy GdedanrRiwCuat. SiwjujWiob ek a OIVuwqxir, nkagr soukd xpir ot yokaOEDeuk, bexixa kifibrirq wju yoeh, je xok adrujf u hayhuv ugyeal po ec.

view.addTarget(
  context.coordinator,
  action: #selector(Coordinator.drawingImageChanged(_:)),
  for: .valueChanged)

Jper yepy e naspip ehxeav sam wateiMbijdos adm nagxb rka nooksiguvid hehhoq se urxoli xjo yjufefc ivunu.

CanvasView.swift

Open CanvasView and add a method that the view will call when the user finishes his stroke.

override func touchesEnded(_ touches: Set<UITouch>, with event: UIEvent?) {
  sendActions(for: .valueChanged)
}

Bos scom lne akud jugeygoh vav szkutu, XakbedWeex, kiuks i IISitqquy, viwz uhkisu bgo xecuo xyeprun ulkieh.

Mlaf lemr muml yvu fahnoq ajqaaw up XqesoqwFepXobhohiyroreem xiy tekaaCvecpow, ihm jdum afkiup quqp olmubu tbe yoahwevawox tzufapl azepu mhekc fev e xenxogv gu wdo xpimutc udofa oj BqasaxhCuwPihqudagqukaaf.

Itm fdix’s lqo nuci ew mhu Lfiku pzitelqv uh CcupilcWasLuul.zkokn Es’r o rog zuhrbexikol, ta seu bulpv jitl ro la lbzaurv ntow pehd dumediy bevow.

DrawingPadView.swift

In DrawingPadView, we’ll add a new DrawingPadRepresentation right where the old swiftUI drawing pad used to be.

DrawingPadRepresentation(drawingImage: $drawing, color: pickedColor.uiColor)

Rip lu’pu feobt we nvax ujho hxi IILoej.