AppDevelopmentQuickGuidesforMastermindsJ.DGauchatwww.jdgauchat.comCoverIllustrationbyPatriceGardenwww.smartcreativz.com

QuickGuidesforMastermindsCopyright©2018byJohnDGauchatAllRightsReservedNopartof thisworkmaybereproducedortransmitted inanyformorbyanymeans,electronic or mechanical, including photocopying, recording, or by any informationstorageorretrievalsystemwithoutthepriorwrittenpermissionofthecopyrightowner.Companies, services, or product names used in this eBook are for identificationpurposes only. All trademarks and registered trademarks are the property of theirrespectiveowners.Apple™,iPhone™,iPad™andiPodTouch™aretrademarksofAppleInc.The content of this guide is a collection of excerpts from the book iOS Apps forMasterminds.Formoreinformation,visitwww.formasterminds.com.The information in this eBook is distributed on an "as is" basis, without warranty.Althougheveryprecautionhasbeentakeninthepreparationofthiswork,neithertheauthornorthepublishershallhaveanyliabilitytoanypersonorentitywithrespecttoany loss or damage caused or alleged to be caused directly or indirectly by theinformationcontainedinthiswork.ThesourcecodeforthiseBookisavailableatwww.formasterminds.comCopyrightRegistrationNumber:11407251stEdition2018

WhatisInsideThisguidewill teachyouthe fundamentalsofappdevelopment for iOS.After readingthisguide,youwillknowtherequirementstodevelopappsforiPhonesandiPads,howtheyarecreated,andwhatyouneedtopublishyourappsintheAppStore.

AboutthisGuideThis guide is a collection of excerpts from the book iOS Apps for Masterminds. Theinformation included in thisguidewillhelpyouunderstandaparticularaspectofappdevelopmentiniOS,butitwillnotteachyoueverythingyouneedtoknowtodevelopanappforAppledevices.IfyouneedacompletecourseonappdevelopmentforiOS,readour book iOS Apps for Masterminds. For more information, visit our website atwww.formasterminds.com.

WhatDoYouNeedThis guide assumes that you haveworkedwith computers before, you know how toinstallsoftware,andthatyouhaveabasicknowledgeaboutiOSandmobileapplicationsingeneral.ForacompletecourseonappdevelopmentforiOS,readourbookiOSAppsforMasterminds.

IMPORTANT: Supporting links, examples, projects, videos, and resources areavailableatwww.formasterminds.com.Apple'sofficialdocumentationisavailableatdeveloper.apple.com. Frameworks and APIs references are available atdeveloper.apple.com/reference.

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TableofContents

APPDEVELOPMENT

Introduction

Overview

RequirementsMobileOperativeSystem

XcodeRunningXcode

DevelopmentProgrammingLanguagesCocoaTouchAPICompiler

AppDevelopmentIntroductionIn2007AppleintroducedthefirstiPhonetothemarket.Thesmartphonewasregardedbymanyasarevolutionarypieceoftechnology,butnotfortherightreasons.Theinnovationspresentedbythisdevicewereclearlychangingourunderstandingoftelecommunicationsandchallengingthepreconceptionswehadofwhataphonecoulddo,butnobody,notevenApple,wasabletopredicttheimpactthatitwouldhaveinthesoftwareindustry. Atfirst,Apple'splanwastofollowthetrend.Theywantedtoprovideanewcommunicationdevicewithenhancedcapabilitiesbutundertheirstrictcontrol.Thedevicewouldbecapableofrunningitsownapplications,alsocalledappsornativeapps,butonlythosecreatedbythecompanywouldbeavailable.Eachuserwouldhavethesameappsaseverybodyelseandonlyaccessthird-partyapplicationsfromthewebandthroughthebrowserthatwasdeliveredwiththesystem.Applewastryingtofocusitsstrategyonwebapplicationsandemergingwebtechnologies,likeeverybodyelse,buttheincrediblepossibilitiesofferedbytheiPhoneinevitablyaltereditsplans. Thenewfeaturesandmobilecapabilitiesintroducedbythispowerfuldevicecaughtdevelopers'attentionallaroundtheworld,andtheinteresttocreatenativeapplicationsgrewfast.Soon,methodstoinstallunauthorizedapplicationswerecreatedandpopularized.Dozensofthird-partyapplicationsweredevelopedandsharedonlinethroughopenmarkets.Thesuccessofthesefirstappsandthewillingnessofuserstoinstallthem(undertheriskofdamagingtheirdevices)madeclearthatnotmanypeopleagreedwiththecompany’sinitialintentions.Itwasevidentthatuserspreferredtotaponaniconandworkwiththeapprightawayratherthanopenabrowser,rememberadomain,typeit,andwaitforthewebapplicationtoload.Theseapplicationswereeasytoaccess,focusedonasinglepurpose,andvisuallymoreappealingthanawebsite.Developerswantedtocreateanduserswantedtoconsumenativeapps. Thisexternalpressure,alongwithinternaldemandsfromexecutivesinApple’sheadquarters,motivatedachangeinSteveJobs’smind,andthecreationoftheAppStorewasannounced.ThecreationoftheAppStorenotonlymeantthatanofficialplacetosellappswasgoingtobeavailable,butalsothatawholesetoftoolswasgoingtobeprovidedbythecompanyitselftocreatethem.TheAppStoreandtheiOSSDK(SoftwareDevelopmentKit)changedeverythingforgood.Developersnowhadtherighttoolstobuildtheirappsandusershadasafeplacetobuythem.Soon,thousandsofnativeappswereavailable,generatinganexcellentalternativetowebapplicationsandcreatingawholenewmarket.ThenewappsattractedmorecustomersforAppledevices,whichmotivatedthecreationofmoreapps,inapositivespiralthatgeneratedbillionsofdollars.Severalapplicationscreatedbydevelopersworkingalonefromtheirbedroomsbecameanovernightsuccess,triggeringagoldrush,theeffectsofwhicharestillvisiblenowadays.

ThenewdistributionchannelsandtheproductiontoolsprovidedbyApplehaveinitiatedagoldenerafordevelopers.Thepossibilityandopportunitiesareinfinite.Nativeapplicationsareheretostay,themarkettheyhavecreatedisgrowingbytheday,andnowyoucanbepartofit.

IMPORTANT:Linkswithadditionalinformation,examples,projects,videos,andresourcesareavailableatwww.formasterminds.com.Apple'sofficialdocumentationisavailableatdeveloper.apple.com.FrameworksandAPIsreferencesareavailableatdeveloper.apple.com/reference.

OverviewThedecisiontocreatetheAppStoreandopentheplatformtodeveloperswasnotaneasyone.SteveJobsdidnotliketheideaofexposinghishighlypraisednewcreationtothesamethreatsofpersonalcomputers.Hedidnotwanthisdevicestobeaffectedbyvirusesorattackedbyhackersandgetabadreputation.HeinsistedonkeepingtheplatformcloseduntilherealizedthattheycouldtakeadvantageofthesystemsalreadydevelopedbyApplefortheiTunesStoretostayincontrolofqualityandsales.Thisdecisiondidnotcomewithoutapricefordevelopers.Thesystemisopenenoughtoallowfullcreativity,butit’sstillunderApple’sstrictsupervision,whichmeansdeveloperscanonlyworkaccordingtothecompany’srules.RequirementsApplerequiresdeveloperstousethesoftwareprovidedbythecompanytocreateappsforitsmobiledevices.ThissoftwareonlyworksinApplecomputersandrequiresthedevelopertohaveanAppleaccount.Forthesereasons,theoptionsareverylimited,butthegoodnewsisthatmostofthethingsweneedareprovidedforfree.

MacComputer—ThisintheorycouldbeanyIntel-basedMaccomputer,butthedevelopmentsoftwarealwaysrequiresthelatestoperativesystem(macOS),soinpracticeweneedarelativelynewcomputer.

AppleDeveloperAccount—Thisisabasicaccountwecangetforfree;itgivesusaccesstotheMemberCenterwherewecanwatchvideos,downloadprogrammingguides,readtheofficialdocumentation,getsamplecodes,andmore.

Xcode—ThisisthesoftwareprovidedbyApplefordevelopment.Thelatestversionisnumber9.It’sfreeandthepackagecomeswitheverythingweneedtocreateourapps,includinganeditor,theSDK(SoftwareDevelopmentKit),andasimulatortotesttheapplications.

AppleDeveloperProgram—Thisisthedeveloperaccountweneedtopublishourapps.MembershiptothisprogramisnotonlyrequiredtopublishourappsintheAppStorebutalsotoimplementserviceslikeiCloud.Atthismoment,themembershipcosts$99USdollarsperyear.

MobileDevice—Thiscouldbeanyofthedevicesavailableinthemarket,includingiPads,iPhones,andiPodsTouch,butatthetimeofpickingonefortestingwehavetoconsiderthatoldmodelsdonotsupportthecurrentversionsofApple’smobileoperativesystem(iOS),andthelatestversionofthissystem,iOS11,onlyrunsondeviceswitha64bitprocessor.Testingourapplicationsonarealdeviceishighlyrecommendedandnecessarybeforepublishing.

Thesetupisrelativelysimple.WehavetogetaMacComputercapableofrunningtheoperativesystemcurrentlyrequiredbyXcode(atthetimeofthiswriting,itismacOSSierra),openanAppledeveloperaccountfromdeveloper.apple.comusingourpersonalAppleID(theonethatiscreatedwhenweinitializedourcomputer),andinstallthelatestversionofXcode(currently9).MobileOperativeSystemiOSisthenameoftheoperativesystemdeliveredbyApplewitheverymobiledevicesold(exceptfortheAppleWatchthathasitsownOScalledwatchOS).Thesystemiscurrentlyinversionnumber11.Althoughwecoulddevelopourapplicationsforoldersystems,thisisnotrecommendedunlesswehaveverystrongreasonstodoso.Statisticsshowthatatanygiventime,thelatestoperativesystemisinstalledinover90%ofactivedevices,andthereforemostdevelopersonlycreateapplicationsforthelatestversionofiOS.

XcodeXcodeisageneral-purposeIDE(IntegratedDevelopmentEnvironment).Itincludesaverypowerfuleditorwithgraphictoolstohelpuswriteourcode,theSDKs(SoftwareDevelopmentKits)forthecreationofsoftwarefortheiOS,macOS,watchOS,andtvOSoperativesystems,andcompilersfortheC,C++,Objective-CandSwiftlanguages.FromXcode,wecanprogramsoftwareforeveryAppleplatformusinganyoftheseprogramminglanguages. XcodeisavailableasanappontheMacAppStore.Todownloadthisapplication,wehavetoopentheAppStorefromLaunchpad(theapplicationorganizerthatcomeswithmacOS)ordoubleclicktheAppStoreiconinsidetheApplicationsfolderinFinder(macOSfileexplorer).FromtheAppStore,wehavetosearchfortheterm"Xcode".ThewindowwillshowtheXcode’siconatthetop(Figure1,number1).Then,wehavetoclickontheGETbuttontodownloadandinstallthesoftware.

Figure1:XcodeintheMacAppStore

RunningXcodeOncethedownloadingprocessisover,thesoftwareisautomaticallyinstalled.ToopenXcode,wehavetogotoLaunchpadandclickontheiconorsearchfortheprograminsidetheApplicationsfolderinFinder.Figure2showsXcode'swelcomescreen.

Figure2:Xcode'swelcomescreen

Thewelcomescreenoffersalistoftherecentprojectsontherightandbuttonsonthelefttoinitiateanewprojectorfindthosealreadycreatedandstoredinarepository.Thefollowingaretheoptionscurrentlyavailable.

Getstartedwithaplayground—ThisoptioncreatesasinglefileandprovidesasimplifiedinterfacecalledPlaygroundthatwecanusetoexperimentandlearnabouttheSwiftlanguageandthebasicframeworksincludedintheSDK.

CreateanewXcodeproject—Thisistheoptionwechoosewhenwewanttocreateanewapplication.TheoptiongeneratesanewXcodeprojectfromatemplatethatprovidesbasicfilesandsettingstostartfrom.

Cloneanexistingproject—Thisoptionallowsustoopenandworkonaprojectstoredonaserver.Itisusedtodownloadaprojectalreadyinitiatedbyotherdevelopersorshareaprojectonline.

DevelopmentEventhoughsomesimpleprojectscouldbedevelopedwithoutprogrammingasinglelineofcode,wealwayshavetowriteourowncodeifwewanttocreateausefulapplication,andforthat,weneedprogramminglanguages.ProgrammingLanguagesSeveralyearsago,AppleadoptedandimplementedalanguagecalledObjective-Ctoallowdeveloperstocreateapplicationsforitsdevices.Duetothetechnicallevelrequiredtoworkwiththislanguage,thespectacularsuccessofApple'smobiledevicesdidnotimpressdevelopersthesamewayasconsumers.Thedemandformoreandbetterapplicationswasgrowingfast,butthecomplicatednatureofthesystemdidnotappealtomostdeveloperswhowereusedtoworkingwithmoretraditionaltools.Tosolvethisproblem,thecompanyintroducedsomeinnovationstoXcodeandengagedin

activeworktopromotetheevolutionofObjective-C.Butnomatterhowhardtheytried,somecomplexfeaturesofthelanguage,suchastheextensiveuseofpointersanditsverbosesyntax,weredifficulttoremoveandwerestillscaringdevelopersaway,especiallywebdeveloperstransitioningfromsimplerlanguageslikeHTML,CSS,andJavaScript. Inthemiddleof2014,withthepurposeofputtinganendtothissituation,thecompanyintroducedanewprogramminglanguagecalledSwift.Swiftpresentsasimplersyntaxthatdevelopersfindfamiliar,whileatthesametimepreservesthatlow-levelnaturenecessarytotakeadvantageofeveryaspectofApple'sdevices.SwiftwasdesignedtoreplaceObjective-Cand,therefore,isthelanguagerecommendedtonewdevelopers.

IMPORTANT:BecauseoftherecentintroductionoftheSwiftlanguage,ahugepartoftheSDKisstillprogrammedinApple'spreviouslanguages(Objective-CandC).Althoughthecompany'sintentionistofocusonitsnewlanguage,themigrationoftheAPIs,documentation,andexamplesfromonelanguagetoanotherwilltakesometime.IfyoucomeacrossexamplesortutorialswritteninObjective-C,thereisaguideprovidedbyApplethatexplainshowthiscodemaybetranslatedtoSwiftcalled"UsingSwiftwithCocoaandObjective-C".Also,youcanalwayslearnthebasicsofObjective-CfromApple'sofficialguide.Formoreinformation,visitourwebsiteandfollowthelinksforthisguide.

CocoaTouchAPIProgramminglanguagesbythemselvescannotdomuch.Theyprovidealltheelementstointeractwiththesystem,butarebasictoolsforthemanipulationofdata.Becauseofthecomplexityoftheinformationrequiredtocontrolsophisticatedtechnologiesandaccesseveryaspectofasystem,itcouldtakeyearstodevelopanapplicationfromscratchworkingwithjusttheinstructionsofaprogramminglanguage.Doingsimplethingslikeprintinggraphicsonthescreenorstoringdatainmemorywouldbecomeanightmareifprogrammershadtodependonthetoolsprovidedbyprogramminglanguagesalone.Forthisreason,thelanguagesarealwaysaccompaniedbysetsofpre-programmedroutinesgroupedinlibrariesandframeworksthatthroughasimpleinterfacecalledAPI(Applicationprogramminginterface)allowprogrammerstoincorporatetotheirappsamazingfunctionalitywithjustafewlinesofcode. XcodecomeswithanSDKthatincludesalltheframeworksandAPIsweneedtoworkwitheverycomponentofAppledevices.InApple’senvironment,thislargegroupofdevelopmenttoolsisreferredtoasCocoaTouchAPI(namedaftertheCocoaAPIcreatedforMaccomputers).Compiler

ComputersdonotunderstandSwiftoranyotherprogramminglanguage.Theselanguageswerecreatedforustogivemachinesinstructionswecanunderstand.Ourcodehastobeconvertedtoelementalordersthatworkatanelectroniclevel,turningmultipleswitchesonandofftorepresenttheabstractionhumansworkwith.Thetranslationfromthelanguagehumansunderstandtothelanguagecomputersunderstandisdonebyaprogramcalledcompiler. Compilershavespecificroutinestotranslateinstructionsfromprogramminglanguagestomachinecode.Theyarelanguageandplatformspecific,whichmeansthatweneedaspecificcompilertoprograminonelanguageandforoneparticulardevice.ThereareafewcompilersavailableforApplesystems,buttheonecurrentlyusedbyXcodeiscalledLLVM.LLVMiscapableofcompilingcodewritteninSwift,C,C++,andObjective-C. Withthecompiler,themachinerytobuildanappiscomplete.Figure3showsalltheelementsinvolved.Therearethreemainsourcesofcodethecompilerusestobuildtheapplication:ourcodeinSwift,theframeworksourprogramrequires,andasetofbasicroutinesnecessaryfortheapptorun(calledApplicationLoopinFigure3).TheprocessstartsfromXcode.Inthisprogramwewriteourcode,accessframeworksthroughtheirAPIs,andconfiguretheapptobecompiled(built).Combiningourcode,thecodesfromtheframeworksourapprequiresandthebasicroutines(ApplicationLoop),thecompilercreatesanexecutableprogramthatmayberuninasimulator,adevice,orsubmittedtotheAppStorefordistribution.

Figure3:BuildinganApp

TheBasics:TheApplicationLoopisagroupofelementalroutines,commontoeveryprogram,thatconnectsyourapptotheoperativesystemandprovidesaloop(acodethatexecutesitselfoverandoveragain)toconstantlycheckforeventsproducedbytheuserorcomingfromthesystem.Althoughyouneverworkdirectlywiththeseroutines,theyareconnectedtoyourcodetoinformthestateoftheprogramthroughtheAppDelegateobject.

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