CS5530 Mobile/Wireless Systems - College of Engineering...

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CS5530Mobile/WirelessSystems

Swift

YanyanZhuangDepartmentofComputerSciencehttp://www.cs.uccs.edu/~yzhuang

UC.ColoradoSprings

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Ref.CN5E,NT@UW,WUSTL2CS5530

• iMacsremoteVNCaccesso VNP:http://www.uccs.edu/itservices/services/network-and-internet/vpn.html

o VNCpassword:cs5530

o PleasesavedatatoZ

o PleasedonotuseiMacsinLibrary

o ITwillupgrade…

Swift


• Whatisit?o AnewprogramminglanguageforAppleproducts

} iOS(ipods,iphones,ipads,etc.),macOS,watchOS,tvOS,future…

} Currentlyatversion3¨ Toseeyourversion:xcrun swift-version

¨ AppleSwiftversion3.0.2(swiftlang-800.0.63clang-800.0.42.1)

} Opensource

o BasedonObjective-CandC.} Classes,instances,properties,methods,inheritance,etc.

Swift


o RequiresanAppleproductfordevelopment} Air,MacBook,MacBookPro,iMac,iTrashCan (MacPro)

o Requiresthe‘Xcode’developmentenvironment,Appleonly.

o Resourcesat:} https://developer.apple.com/

Xcode Playground


o Aninteractiveworkenvironmentthatallowsyouupdatevaluesreal-timeandseeresults.

o A‘project’optioninXcode.

o NewforiPadiOS10!!!

Xcode Playground


Swift


• Quickoverviewofthelanguageo Assignments

o ControlFlow

o FunctionsandClosures

o ObjectsandClasses

o EnumerationsandStructures

o Protocols

o ErrorHandling

Swift- Overview


• “Don’tneedtoimportaseparatelibraryforfunctionalitylikeinput/outputorstringhandling.

• Codewrittenatglobalscopeisusedastheentrypointfortheprogram,soyoudon’tneedmain().

• Don’tneedtowritesemicolonsattheendofeverystatement.”• ExcerptFrom:AppleInc.“TheSwiftProgrammingLanguage(Swift3.0.1).”iBooks.

https://itun.es/ca/jEUH0.l

Swift- Assignments


o Typescanbe‘inferred’

o Canbeexplicit

o NOimplicittypeconversions} Valuesinstringsbyusinga“\”

let apples = 3

let applySummary = “I have \(apples) apples.”

Keyword Description

let Usedforconstants.Doesnotneedtobeknownatcompiletimebutmustbeassignedavalueexactly once.

var Usedforvariables.

Swift- Assignments


o Typescanbe‘inferred’o Canbeexplicito NOimplicittypeconversions

} Valuesinstringsbyusinga“\”let apples = 3

let applySummary = “I have \(apples) apples.”

} Valuesareneverimplicitlyconvertedtoanothertype.Ifneedtoconvertavaluetoadifferenttype,explicitlymakeaninstanceofthedesiredtype.

“TheSwiftProgrammingLanguage(Swift3.0.1).”

Keyword Description

let Usedforconstants.Doesnotneedtobeknownatcompiletimebutmustbeassignedavalueexactly once.

var Usedforvariables.

Swift- Assignments


• Assignmentso Dictionariesandarraysuse[]

var shoppingList = [“hp”, “apple”, “microsoft”]

shoppingList[1] = “Lenovo”

var occupations = ["Malcolm": "Captain", "Kaylee": "Mechanic"]

occupations["Jayne"] = "Public Relations”

o Emptyarraysordictionarieslet emptyArray = [String]()

Let emptyDictionary = [String: Float]()

Iftypeinformationcanbeinferred,canwriteanemptyarrayas[]andanemptydictionaryas[:]

• DataTypeso Typicaldatatypesavailable.

} String,Float,Double,Bool,Int/Uint,Character,Optional

Swift– ControlFlow


• For/ifexampleo Ifconditionmustbeexplicit

o ifscore{..}isanerror

Keyword Description

if, switch Usedforconditionals.Parenthesisaroundvariableareoptional.Bracesaroundconditional bodyarerequired.

for-in, for, while, repeat-while

Usedfor loops.Parenthesisaroundvariableareoptional.Bracesaroundloopbodyarerequired.



• Switch



• Switcho letcanbeusedinapatterntoassignvalue

o Noneedtobreak} Onlyonematch



• for-ino Iterateoveritemsinadictionarybyprovidingapairofnamestouseforeachkey-valuepair.

o Dictionariesareunordered!



o While&repeat-while} SameasCorJava’swhile&do-while.

} repeat{…}whilesome-condition

o Forloopsstillthesame} Thoughyoucanuse..< or ... tomakeranges.

¨ 0..<7 non-inclusiveupperbound.

¨ for i in 0..<7 { … }

¨ 0...7 inclusiveupperbound

¨ for i in 0...7 { … }

Swift– Functions&Closures


• Usefunc todeclareafunctiono à toindicatereturntype

o Useatupletomakeacompoundvalue:returnmultiplevaluesfromafunction

} Elementsofatuplecanbereferredtobynameorbynumber

} Definedas……à (min: Int, max: Int, sum: Int)

} Accessasresults.sum, or results.2



o Cantakevariablearguments,collectsintoanarrayforyou.

o Canbenested.



o Functionsarefirst-classtypes:theycanreturnanotherfunctionasareturn-value

o Cantakeanotherfunctionasoneofitsarguments



• Aclosureisablockofcodethatcanbecalledlater(anonymousfunction)

• Codeinaclosurehasaccesstoo Variablesandfunctionsthatwereavailableinthescopewheretheclosurewas

created,eveniftheclosureisinadifferentscopewhenitisexecutedo Youcanwriteaclosurewithoutaname(functionname)

} Surroundcodewithbraces{}} Use‘in’toseparatetheargumentsandreturntypefromthebody

¨ Indicatesthatdefinitionofclosure’sparametersandreturntypehasfinished,andthebodyoftheclosureisabouttobegin

Syntax:{(parameters)->returntypein

statements}



o Concise1:iftypealreadyknown,youcanomittypesofparametersand/orreturntype.

o Concise2:canrefertoparametersbynumberinsteadofname

Swift– Objects&Classes


• Classeso Aswe’dexpect.o Use‘init’asinitializer/constructor.

o Use‘deinit’asdeinitializer /destructoro Instantiationbyreferencingclassnamefollowedby()

} var shape=Shape()



• Classeso Toinherit,subclassesincludetheirsuperclassesnameaftertheirclassname,separatedbya:} classSquare:Shape

} classViewController:UIViewController,UITextFieldDelegate

o Methodsinasubclassthatoverridethesuperclass’simplementationaremarkedwithoverride} Overridingamethodbyaccident,withoutoverride,isdetectedbythecompilerasanerror



o Properties canhave‘getter’and‘setter’methods.} SimilartoJava,C#,VB.Net

} Note‘newValue’isimplicitlydefinedforusasthenewvalue(seecodeexample)

} Canbeexplicitbydeclaringthesetteras:¨ set(<parameter_name>)

¨ set( mySide ) { ... }

¨ Thereisnotypedeclarationneededbecausethepropertydefinedit.



o Inheritance} Class:parent

} Overridewith‘override’keyword.

} Callparentmethodswith‘super.’keyword.

Swift– Enumerations&Structures


• Enumerationso Use‘enum’tocreateanenumeration

} Swiftassignsrawvaluesstartingatzeroandincrementsby1,butcanchangethisbyexplicitlyspecifyingvalues

o Canhavemethodsassociatedwiththem.

Swift– Enumerations&Structures


• Structureso Use‘struct’tocreateastructure.

o Supportmanyofthesamebehaviorsasclasses,includingmethods&initializers.

o Structuresarepassedbyvalue!(classesbyreference)

Swift– Protocols&Extensions


• Protocolso It’sbasicallyan‘interface’fromotherOOlanguages.o Use‘protocol’todeclareaprotocol.

o ‘mutating’indicatesafunctionchangingthestruct.} Notneededinclassredefinitionsasclassmethodscanalwaysmodifytheclass.

} Neededinstructurestoindicatethatthemethodwillmodifythestructure.

o Classes,enumerationsandstructs canalladoptprotocols.

Swift– Protocols&Extensions


• Useextensionstoaddfunctionalitytoanexistingtype

Swift– ErrorHandling


• ErrorHandlingo RepresenterrorsusinganytypethatadoptstheErrorprotocol.

o Use‘throw’tothrowanerrorand‘throws’todenoteafunctionthatcanthrowanerror.

Swift– ErrorHandling


• ErrorHandlingo do/catch

} Indoblock,markcodethatcanthrowanerrorbywritingtry infront

} Incatchblock,theerrorisautomaticallygiventhenameerrorunlessyougiveitadifferentname

} Canprovidemultiplecatchblocksthathandlespecificerrors

Swift– Comments


Let’sPractice!


• Printstrings(useterminator:””todisable\n)o letlabel="Thewidthis"o letwidth=94o print(label+String(width))o //comparewithprint(label+String(width),terminator:””)

o letapples=3o letappleSummary ="Ihave\(apples)apples."

o letoranges=5o letfruitSummary ="Ihave\(apples+oranges)piecesoffruit."

Let’sPractice!


• Q1:What’swrongwiththefollowingcode?

• Q2:

SwiftResources


• Contentwasusedfromthesewebsiteswhereappropriate.Thesesitescontainquiteabitmoreinformationandwouldmakeagreatresourceforyou.

https://developer.apple.com/

https://itunes.apple.com/us/book/the-swift-programming-language/id881256329?mt=11

https://www.hackingwithswift.com/read

https://www.hackingwithswift.com/example-code

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