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![closuresImplicit returns from
let sum = { (lhs: Int, rhs: Int) in
lhs + rhs
}
[1, 2, 3, 4, 5]
.map { $0 * 2 }
[true, false, true]
.filter { $0 }](https://image.slidesharecdn.com/swiftinswiftui-191114105729/75/Swift-in-SwiftUI-7-2048.jpg)
![SwiftUI
ForEach(["Data1", "Data2", "Data3"], id: .self)
ForEach([🐶, 🐱, 🐰], id: .id)](https://image.slidesharecdn.com/swiftinswiftui-191114105729/75/Swift-in-SwiftUI-53-2048.jpg)
![SwiftUI
ForEach([🐶, 🐱, 🐰])
ForEach(["Data1", "Data2", "Data3"], id: .self)
ForEach([🐶, 🐱, 🐰], id: .id)](https://image.slidesharecdn.com/swiftinswiftui-191114105729/75/Swift-in-SwiftUI-54-2048.jpg)
![SwiftUI
ForEach([🐶, 🐱, 🐰]) { ... }
let 🐶 = Animal(id: 1, name: " ", age: 5)
let 🐱 = Animal(id: 2, name: " ", age: 2)
let 🐰 = Animal(id: 3, name: " ", age: 3)](https://image.slidesharecdn.com/swiftinswiftui-191114105729/75/Swift-in-SwiftUI-55-2048.jpg)
![SwiftUI
ForEach([🐶, 🐱, 🐰]) { ... }
let 🐶 = Animal(id: 1, name: " ", age: 5)
let 🐱 = Animal(id: 1, name: " ", age: 2)
let 🐰 = Animal(id: 1, name: " ", age: 3)](https://image.slidesharecdn.com/swiftinswiftui-191114105729/75/Swift-in-SwiftUI-56-2048.jpg)
![SwiftUI
ForEach([🐶, 🐱, 🐰]) { ... }
let 🐶 = Animal(id: 1, name: " ", age: 5)
let 🐱 = Animal(id: 1, name: " ", age: 2)
let 🐰 = Animal(id: 1, name: " ", age: 3)](https://image.slidesharecdn.com/swiftinswiftui-191114105729/75/Swift-in-SwiftUI-57-2048.jpg)
Uploaded byBongwon Lee
Swift in SwiftUI
The document discusses several Swift Evolution proposals including: - Implicit returns from single-expression functions and closures which allows omitting the return keyword from functions/closures with a single expression. - Opaque result types which allow abstracting away types using some to preserve type identity and information hiding. - The Identifiable protocol which provides a standard way to identify values based on an ID property to enable change tracking in SwiftUI lists and other APIs. - Property wrappers which define custom attributes to encapsulate property storage and behavior, eliminating boilerplate and providing patterns to define properties like @State, @Binding, @Published etc.
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Swift in SwiftUI
- 3.
- 4.
- 5. SE-0255 SE-0244 SE-0261 Implicit returns fromsingle-expression functions Opaque Result Types Identifiable Protocol SE-0258 Property Wrappers
- 6. Implicit returns fromsingle- expression functions SE-0255
- 7. closuresImplicit returns from letsum = { (lhs: Int, rhs: Int) in lhs + rhs } [1, 2, 3, 4, 5] .map { $0 * 2 } [true, false, true] .filter { $0 }
- 8. functionsImplicit returns from funcsum(_ lhs: Int, _ rhs: Int) -> Int { return lhs + rhs }1
- 9. functionsImplicit returns from funcsum(_ lhs: Int, _ rhs: Int) -> Int { lhs + rhs }1
- 10. functionsImplicit returns from funcsum(_ lhs: Int, _ rhs: Int) -> Int { let result = lhs + rhs result }1
- 11. Implicit returns fromfunctionssingle-expression func sum(_ lhs: Int, _ rhs: Int) -> Int { let result = lhs + rhs result }1
- 12. Implicit returns fromfunctionssingle-expression func sum(_ lhs: Int, _ rhs: Int) -> Int { let result = lhs + rhs return result }1
- 13. Computed property struct ContentView:View { var body: some View { Text("Hello world!") }1 }1
- 14. Computed property struct ContentView:View { var body: some View { let text = "Hello world!" Text(text) }1 }1
- 15. struct ContentView: View{ var body: some View { let text = "Hello world!" return Text(text) }1 }1 Computed property
- 16. Single-expression struct ContentView: View{ var body: some View { Text("Hello world!").font(.title).bold() }1 }1
- 17. Single-expression struct ContentView: View{ var body: some View { Text("Hello world!") .font(.title) .bold() }1 }1
- 18. Evaluating an expression •Returns a value • Causes a side effect • Both
- 19. • Ternary ConditionalOperator Expression vs Statement return .random() ? true : false if .random() { return true } else { return false } • If - else
- 20. • Ternary ConditionalOperator Expression vs Statement return .random() ? true : false if .random() { return true } else { return false } • If - else Expression Statement
- 21. Expression vs Statement varbody: some View { .random() ? Text("true") : Text("false") }1 var body: some View { if .random() { Text("true") } else { Text("false") } } • Ternary Conditional Operator • If - else Expression Statement
- 22. Expression vs Statement varbody: some View { .random() ? Text("true") : Text("false") }1 var body: some View { if .random() { return Text("true") } else { return Text("false") } } • Ternary Conditional Operator • If - else Expression Statement
- 23. • Function,Computed property Implicitreturns from single-expression functionsSE-0255 • Single-expression • Implicit return
- 24.
- 25. some struct ContentView: View{ var body: some View {1 Text("Hello SwiftUI!") }1 }1
- 26. without some struct ContentView:View { var body: View {1 Text("Hello SwiftUI!") }1 }1
- 27. Error - Viewhas associated type struct ContentView: View { var body: View { Text("Hello SwiftUI!") }1 }1 protocol View { associatedtype Body : View var body: Self.Body { get } }1
- 28. View return type varbody: Text {1 Text("Hello SwiftUI!") }1
- 29. View return type varbody: Text {1 Text("Hello SwiftUI!") .foregroundColor(.white) .background(Color.black) }1
- 30. var body: ModifiedContent<Text, _BackgroundModifier<Color>> {1 Text("HelloSwiftUI!") .foregroundColor(.white) .background(Color.black) }1 View return type
- 31. var body: ModifiedContent<VStack<TupleView<(ModifiedContent<I mage, _AspectRatioLayout>,ModifiedContent<Text, _BackgroundModifier<Color>>)>>, _PaddingLayout> {1 VStack {2 Image("SwiftUI") .resizable() .scaledToFit() Text("Hello SwiftUI!") .foregroundColor(.white) .background(Color.black) }.padding() }3 View return type
- 32. var body: someView {1 VStack {2 Image("SwiftUI") .resizable() .scaledToFit() Text("Hello SwiftUI!") .foregroundColor(.white) .background(Color.black) }.padding() }3 Opaque type
- 33. func genericFunction<T: Animal>(_animal: T) { ... // Callee - abstracted type } // T == Dog, Caller pick the type genericFunction(Dog()) Abstracted type - Generic // T == Cat genericFunction(Cat())
- 34. func opaqueTypeFunction() ->some Animal { Dog() // Callee pick the type } // Caller - abstracted type let animal: some Animal = opaqueTypeFunction() Abstracted type - Opaque type
- 35. Protocol return type funcprotocolReturnType() -> Animal { .random() ? Dog() : Cat() } // Dog? Cat? let animal: Animal = protocolReturnType()
- 36. Self or associatedtype func someFunction( lhs: Equatable, rhs: Equatable ) -> Bool { ... } func someFunction() -> Hashable { ... } var someProperty: Collection { ... }
- 37. Type identity func returnConcreteType()-> some Animal { let result: Animal = Dog() return result } func returnConcreteType() -> some Animal { Dog() }
- 38. Type identity func genericFunc<T:Equatable>( lhs: T, rhs: T ) -> Bool { lhs == rhs // Same generic type T } // Caller pick the type genericFunction(lhs: "Swift", rhs: "UI")
- 39. Type identity func opaqueTypeFunc()-> some Equatable { .random() ? "Swift" : 5.1 } func opaqueTypeFunc() -> some Equatable { // Callee pick the type // Same return type .random() ? "Swift" : "UI" }
- 40. var body: someView { .random() ? Rectangle() : Circle() } SwiftUI var body: some View { .random() ? AnyView(Rectangle()) : AnyView(Circle()) }
- 41. • Hiding typeinformation Opaque Result TypesSE-0244 • Preserving type information • Reverse generic
- 42.
- 43. struct Animal: Equatable{1 let name: String let age: Int }1 let 🐶 = Animal(name: " ", age: 5) let 🐰 = Animal(name: " ", age: 5) Equatable 🐶 == 🐰 // true
- 44. struct Animal: Equatable{1 let name: String let age: Int }1 Equatable
- 45. struct Animal: Equatable{1 let id: Int let name: String let age: Int }1 Equatable
- 46. struct Animal: Equatable{ let id: Int let name: String let age: Int } Equatable let 🐶𝞪 = Animal(id: 1, name: " ", age: 5) let 🐶𝞫 = Animal(id: 1, name: " ", age: 6)
- 47. Equatable // false 🐶𝞪 ==🐶𝞫 // true 🐶𝞪.id == 🐶𝞫.id
- 48. Equatable // false 🐶𝞪 ==🐶𝞫 // true 🐶𝞪.id == 🐶𝞫.id // Identity Operator, Reference type 🐶𝞪 === 🐶𝞫
- 49. Identifiable Protocol protocol Identifiable{ associatedtype ID : Hashable var id: Self.ID { get } }
- 50. Identifiable Protocol protocol Identifiable{ associatedtype ID : Hashable var id: Self.ID { get } } extension Animal: Identifiable {}
- 51. Diff algorithm let 🐶𝞪= Animal(id: 1, name: " ", age: 5) let 🐶𝞫 = Animal(id: 1, name: " ", age: 6) ... let 🐶𝞬 = Animal(id: 1, name: " ", age: 10) ... 🐶𝞪 <---> 🐶𝞫 <---> 🐶𝞬
- 52. SwiftUI extension List { init<Data,RowContent>(_ data: Data, ... ) where Data.Element : Identifiable } extension View { func alert<Item>(item: Binding<Item?>, ... ) -> some View where Item : Identifiable }
- 53. SwiftUI ForEach(["Data1", "Data2", "Data3"],id: .self) ForEach([🐶, 🐱, 🐰], id: .id)
- 54. SwiftUI ForEach([🐶, 🐱, 🐰]) ForEach(["Data1","Data2", "Data3"], id: .self) ForEach([🐶, 🐱, 🐰], id: .id)
- 55. SwiftUI ForEach([🐶, 🐱, 🐰]){ ... } let 🐶 = Animal(id: 1, name: " ", age: 5) let 🐱 = Animal(id: 2, name: " ", age: 2) let 🐰 = Animal(id: 3, name: " ", age: 3)
- 56. SwiftUI ForEach([🐶, 🐱, 🐰]){ ... } let 🐶 = Animal(id: 1, name: " ", age: 5) let 🐱 = Animal(id: 1, name: " ", age: 2) let 🐰 = Animal(id: 1, name: " ", age: 3)
- 57. SwiftUI ForEach([🐶, 🐱, 🐰]){ ... } let 🐶 = Animal(id: 1, name: " ", age: 5) let 🐱 = Animal(id: 1, name: " ", age: 2) let 🐰 = Animal(id: 1, name: " ", age: 3)
- 58. • Distinguish theidentity of an entity from the state Identifiable ProtocolSE-0261 • Identify changes to the state • Value type identity
- 59.
- 60. struct ContentView: View{ @State private var isOn: Bool = false var body: some View { Toggle(isOn: $isOn) { Text("Label") } } } SwiftUI
- 61. struct ContentView: View{ @State private var isOn: Bool = false var body: some View { Toggle(isOn: $isOn) { Text("Label") } } } SwiftUI @State @Binding @ObservedObject @EnvironmentObject @Environment
- 62.
- 63. struct SomeType { varsomeValue = 0 lazy var someLazyValue = self.someValue + 1 }1 lazy
- 64. struct SomeType { varsomeValue = 0 lazy var someLazyValue = self.someValue + 1 lazy var anotherLazyValue = self.someValue * 2 }1 lazy
- 65. Boilerplate var isLoggedIn: Bool{ get { UserDefaults.standard.bool(forKey: "IS_LOGGED_IN") } set { UserDefaults.standard.set(newValue, forKey: "IS_LOGGED_IN") } }
- 66. Boilerplate var isLoggedIn: Bool{ get { UserDefaults.standard.bool(forKey: "IS_LOGGED_IN") } set { UserDefaults.standard.set(newValue, forKey: "IS_LOGGED_IN") } } var isFirstLogin: Bool { get { UserDefaults.standard.bool(forKey: "IS_FIRST_LOGIN") } set { UserDefaults.standard.set(newValue, forKey: "IS_FIRST_LOGIN") } }
- 67. Wrapper Type @propertyWrapper struct UserDefault<Value>{ let key: String var wrappedValue: Value? { get { UserDefaults.standard.object(forKey: key) as? Value } set { UserDefaults.standard.set(newValue, forKey: key) } } }
- 68. Custom attribute struct User{ @UserDefault(key: "IS_LOGGED_IN") var isLoggedIn: Bool @UserDefault(key: "IS_FIRST_LOGIN") var isFirstLogin: Bool }
- 69. Custom attribute struct User{ @UserDefault(key: "IS_LOGGED_IN") var isLoggedIn: Bool @UserDefault(key: "IS_FIRST_LOGIN") var isFirstLogin: Bool } var user = User() user.isLoggedIn = true user.isFirstLogin = false print(user.isLoggedIn ?? false) print(user.isFirstLogin ?? true)
- 70. Synthesized property @UserDefault(key: "IS_LOGGED_IN") varisLoggedIn: Bool
- 71. Synthesized property @UserDefault(key: "IS_LOGGED_IN") varisLoggedIn: Bool private var _isLoggedIn: UserDefault<Bool> = UserDefault<Bool>(key: "IS_LOGGED_IN") var isLoggedIn: Bool { get { _isLoggedIn.wrappedValue } set { _isLoggedIn.wrappedValue = newValue } } // Synthesized property
- 72. Synthesized property struct UserDefault<Value>{ var projectedValue: Self { get { self } set { self = newValue } } }
- 73. Synthesized property struct UserDefault<Value>{ var projectedValue: Self { get { self } set { self = newValue } } } struct User { var $isLoggedIn: UserDefault<Bool> { get { _isLoggedIn.projectedValue } set { _isLoggedIn.projectedValue = newValue } } }
- 74. Synthesized property isLoggedIn //Computed Property _isLoggedIn // Stored Property, Private $isLoggedIn // Computed Property, Optional @UserDefault(key: "IS_LOGGED_IN") var isLoggedIn: Bool
- 75. • Allow definingpatterns for properties Property WrappersSE-0258 • Provides the storage for a property • Eliminate boilerplate code