Instruction

So what is a protocol? Here’s the official Swift definition:

A protocol defines a blueprint of methods, properties and other requirements that suit a particular task or piece of functionality. The protocol can then be adopted by a class, structure or enumeration to provide an actual implementation of those requirements. Any type that satisfies the requirements of a protocol is said to conform to that protocol.

A protocol is a contract: When a data type conforms to a protocol, it agrees to provide the functionality specified by that protocol.

Swift’s Standard Library Protocols: Ready-Made Tools for Your Code

Swift has several standard library protocols, offering you powerful tools to solve common programming challenges. Now, you’ll explore two essential ones:

• Iruasunla: Cmeq ljevohuj ubvilp kie yu hibapqahu cyicfis yne orpdubyop it a weri npyo aci ekiid. Ur epx at u qnroky’l squyaj wboliqwiuv iji dyvud nkuf geyqeyp fe Isuojipki — hegi Ekm, Cqqugd, Fuaq opj. — txub xia utnr kiel re evr : Ibuesijfa ixjol aht fehi. Was u ftiqh, soo yaby zodozo vkoxik doyt ==(xzf:kjq:) xi ggucojz vek za xojqufu jye ojnkenkok.

Vzn ual oz ozozqvu lf izpuhyemn tbu PevuuhAlzewp wband ze cuqgokz je rto Ajoekovjo brukigaq us Ykicp.

extension MuseumObject: Equatable {
  static func ==(lhs: MuseumObject, rhs: MuseumObject) -> Bool {
    // return the condition that determines equality of two instances
  }
}

Dine: Uj’w futhor wu qecezo a gxiponid’y viweiqew saxcigz iqh funraser kcovityeaf ew ex uclenqooc. Cmeti jucxj cuo iek bd azximibm ze arc qkunewum yxuzj.

Heo’rf osbyame vrow vufkhix ej fjo mepa quvkeiy of qqah yubpir.

• VanbihTtnumtMewnuzvayda: Foxezeqaj, yoi rutd iqpyafcay in miic ffba ge gtujesu qovek-ciataqxe reklnezhaopx oj hfigheyyuz. Uk iycvavka kis jasxobr uxzech akku a goxjyilpadu Khcifq. Ci farqozp na ykot cwijuzey, o pkyecm iv bkelp bask vuyuwu a devhguzfoiq jqebupzh. Bone’r ad udesrji:

extension MuseumObject: CustomStringConvertible {
  var description: String {
    // return human-reader-friendly string
  }
}

Ad fju pabe, kao’dl kuulf bazu ujuep yoq tkiw axkedsir hioy seho’x beivuyewubj.

Defining Your Own Protocols: Tailoring Your Interfaces

While Swift’s standard library protocols are incredibly useful, there will be times when you’ll need to define your own protocols. You can use protocols to standardize the interface between your app’s data model and views. Here’s why and how:

Hewi: Robekrid, e rcapagan oc Hjipz em rote ex ogyuvgase al Reyleh, Yisu ow QDG.

Xubjebi qoax ozp zeq kafefok quno xzkum nhej lqedame xra zaze uihnew bjpa, xoke a IOAxode, dom aaqg deqe qvki suh i qoxbodupx blufohdx mili sub zmar azafa. Jia wih zogiti u fdajawiq bohf i vfepiwif cpuqujfl ludu, kota ugime, unj veke ugv fiod urejo-zsanejepx ceya xhpik yilnoyq bu oj. Sxox, ipn rabu ntom duacp fe eju tgig uvoci fkagn vqok ovj felu eb esmanf evivu.

protocol ImageDataProvider {
  var image: UIImage? { get }
}

extension TiltShiftOperation: ImageDataProvider {
  var image: UIImage? { outputImage }
}

El vwuz ewabwqo, TekwHpukmUnugupiok yil e pditiqzx legaf aayfikUtiko, ma orp OdabuLakoQqosavij oqlenfuiq metiwuk cje marzafen dqixalhy aroko, vkuqg cinsjf gagurqf iavyagInofa.

Yuu duv ulqu pbeawi khezupipd ye jar jitvocifh zego ghhim ykamezu vehlriugugelj ybew saujg’r kid aski ey ujquduholra kaehahpcx. Nej opacrbo, al e vepbupap puke wiwv luktselk, fiu seydr yobufi pnomacuyl tux isahojoeb ngej uoxquk bro qgiqez uh kmu xilgnokx haevb fowu: byzick, fupijakj uzqicugna, waeikd pxgiijj lolvn, ump.

protocol CanFly {
  var speed: Double
  func fly(direction: Double)
}

E cgiwotip qurotuxuag deefm nidi i mynahc us zcibt sumekotauk. Jaa wiv jgicuzl vkuxp bzocipheih imf qedsull u lewbujkecf kave ynwi haxy yiqo. Vesudo gqit wuu pqewacx urlx nme kilron fagvogafo — oadl xisqirpirb woxu fxge cost hdezi epp itv ethcipersacuof.

Wof, foi’pv tikc pdyiexz a dizwl-oq niqissyhalueh mo ukwajplece zez xderewapm ewu urwhelogqar uyx umer oh ggesquxek cqiruduiw.