SwiftUI shi ne declarative UI framework na Apple: kana bayyana yadda UI zai kasance don wani state, kuma framework ɗin ke gano yadda zai render da sabunta shi. Ba ka ƙara sauya views da hannu kamar a UIKit ba — kana sauya state, sai UI ta sake render kai tsaye.
View yana bin protocol kuma yana dawo da abin da yake ƙunshe daga computed property. pure function ne na properties na view.
Viewbodybodystruct Counter: View {
@State private var count = 0 // source of truth
var body: some View { // opaque return type
VStack(spacing: 12) {
Text("Count: \(count)") // re-reads count each render
Button("Increment") {
count += 1 // mutating state triggers re-render
}
}
}
}
some View opaque return type ne: yana nufin "wani takamaiman concrete View type, wanda compiler ke yanke shawara a kansa." Yana ba ka damar dawo da nested view types masu rikitarwa ba tare da rubuta su gabaki ɗaya ba, tare da kiyaye type a static don performance.
label.text = "Count: \(count)" — kana turawa kowane sauyi.Text("Count: \(count)") — kana bayyana dangantakar sau ɗaya; framework ɗin ke sake kiran body lokacin da count ya sauya sannan ya diff sakamakon.Views suna da nauyi kaɗan kuma structs ne, masu araha don ƙirƙira da zubarwa a duk lokacin sauyin state. SwiftUI yana riƙe render tree na ƙasa kuma yana amfani da bambance-bambancen kawai.
Declarative model yana kawar da wani gungun UIKit bugs inda UI ke rabuwa da data. Fahimtar cewa ana sake gudanar da body a duk sauyin state — kuma dole ne ya kasance cheap pure function — shi ne tushen komai a SwiftUI, daga state zuwa performance.
Ɗakin karatu na tambayoyin hira na IT tare da amsoshi cikakke — daga Junior zuwa Senior.
Ba da Gudummawa