CS4720

iOSAppComponents

CS4720– MobileApplicationDevelopment

CS4720

iOSArchitecture

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CS4720

BuildingBlocks• UIApplication

– Themainentrypointforyourapp– Eachapphasexactlyoneinstanceofthisclass– ProvidesthemaininterfacebacktotheOS– HandlesallincominginfofromtheOS(suchastouchevent,memorywarnings,incomingphonecall,etc.)

– Passesthesemessagesoffto…

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CS4720

BuildingBlocks• UIApplicationDelegate

– Managestherunningofyourapp– Handles“major”events,likeappswtiching,appinitialization,etc.

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CS4720

AppDelegate.swift

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import UIKit

@UIApplicationMainclass AppDelegate: UIResponder, UIApplicationDelegate {

var window: UIWindow?

CS4720

AppDelegate.swift

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func application(_ application: UIApplication, didFinishLaunchingWithOptionslaunchOptions: [UIApplicationLaunchOptionsKey: Any]?) -> Bool {return true

}

CS4720

OtherComponents• UIDocument: allowsforinternalappdocumentsanddatastores

• ViewController:managesallviews(scenes)fortheapp

• UIWindow:theonewindowoftheiOSdevice(onlyhavemoreifexternaldisplay)

• ViewObjects:allthewidgetsinascene

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TheMainAppLoop

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TheMainAppLoop• TheOSreceivesinputandpassesittotheUIApplication

• WhichpassesittotheUIApplicationDelegate

• WhichpassesittotheUIWindow• WhichpassesittothecurrentlyseenViewController

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CS4720

TheMainAppLoop• Othereventsarepassedtothe“FirstResponder”objectthatisavailable

• Everythingthatcanacceptandrespondtoaneventisaresponderobject

• Thefirstresponderobjectisthetop-leveldesignatedobjectinaviewtohandleevents

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CS4720

AppStates

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AppStates• applicationWillEnterForeground – startingtomovetoactivestate

• applicationDidBecomeActive – calledrightbeforeviewdisplayed

• applicationWillResignActive – firstcallbeforegoingintobackground

• applicationDidEnterBackground – nowisinbackground

• applicatinoWillTerminate – willend

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OnLaunch• application comesinwithdidFinishLaunchingWithOptions

• CheckdictionarylaunchOptions forinfoonwhywaslaunched(somewhatlikelookingattheIntent)

• Anyappnotrespondingin5secondsiskilled• Startinitialization• UIKit grabsfirststoryboardandViewController

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CS4720

InsidetheView

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CS4720

UsingSegues• InsteadofIntentslikeAndroid,we’lluseSeguestopassdatabetweenScenes/ViewControllers

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CS4720

MVCiniOS• WeagainseeModel-View-Controlleraspartofthefoundationforamobilesystem

• BecauseofthenatureofObjective-CandNeXTSTEP,MVCisoneoftheprimarydesignpatternsforbothiOSandOSX

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MVCiniOS

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MVCiniOS

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MVCiniOS• Model:Thebaseclassesyouwritetoholddata

– CouldsubclassNSObject/Object– Couldconnecttoadatabaseorotherdatasource– Couldbeasimpleclassyouwrite

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MVCiniOS• View:Anyrectangulardrawable objectonthescreen– VariousStack,Table,andCollectionViews– Image,Text,PickerViews– MapandWebKit View– SceneKitView(for3Dscenes)– Managesdrawingitsareaonthescreen– Cancontainotherviews(orbecontained)– Respondstotouchandotherevents

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CS4720

MVCiniOS• Controller:TheViewController class

– EachViewController managesahierarchyofViews– Theview propertyoftheclasscontainstheroot– Viewsareaccesslazily;thatis,theyareonlyloadedwhenneeded

– Updatesthecontentsoftheviews,usuallyinresponsetochangestotheunderlyingdata

– Respondstouserinteractionswithviews– Resizesviewsandmanagesthelayoutoftheoverallinterface

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BuildingupinMVC• Startbyconsideringyourdata

– Wheredoesitcomefrom?– Howwillyoustoreit?– Whatsortofaccessdoyouneedfromit?

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BuildingupinMVC• Storyboardyouridea

– JustaswithAndroid,layouteachscreen– Whatviewsmakeupeachscreen?

• Text?• ATable?• AnImage?

– Whathappenswhenyoutouchorswipeoneachview?Oronthescreen?

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CS4720

BuildingupinMVC• CreatetheappropriateControllertype• AddViewstotheControllertogetthelayoutthewayyouwantit

• Startwithdummydata• Runinthesimulatoroften!• Checkandadjustyourconstraintstogeteverythingonscreen

• Testrotation!

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BuildingupinMVC• InyourStoryboard,linkthevariousViewsbacktothecodeusingctrl-click/drag

• Dothesameforbuttonsandothercontrols• Loaddataasneededtorefreshtheview(oftenhappensautomatically)

• Addincodetohandleuserevents,liketouchesandswipes

• AddNavigationControllerstoallowforswitchingbetweenscenes

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