Gist for geekbrains lecture №5. SwiftUI course

PropertyWrappersGeekbrains.swift

class MyClass {
    
    @Logged(formatString: "HH:mm dd.MM.yyyy") var myProperty = 0
    
    init() {
        print(type(of: _myProperty))
        print(type(of: $myProperty))
        print(type(of: myProperty))
    }
}

protocol MyProtocol {
    associatedtype Value
    var myProperty: Logged<Value> { get set }
}

@propertyWrapper struct Logged<Value> {
    private var value: Value
    private let dateFormatter: DateFormatter
    
    init(wrappedValue: Value, formatString: String) {
        self.value = wrappedValue
        self.dateFormatter = DateFormatter()
        self.dateFormatter.dateFormat = formatString
    }
    
    private func get() -> Value {
        let dateString = dateFormatter.string(from: Date())
        print("\(dateString). myProperty read: \(value)")
        return value
    }
    
    private mutating func set(_ newValue: Value) {
        let dateString = dateFormatter.string(from: Date())
        print("\(dateString). myProperty set to: \(newValue)")
        value = newValue
    }
    
    public var wrappedValue: Value {
        get {
            get()
        }
        set {
            set(newValue)
        }
    }
    
    public var projectedValue: Self {
        return self
    }
    
//    public var projectedValue: String {
//        return "SomeString"
//    }
}

//myClass._myProperty
MyClass().myProperty._value

@propertyWrapper struct Trimmed {
    let value: String
    
    init(wrappedValue: String) {
        self.value = wrappedValue
    }
    
    var wrappedValue: String {
        get {
            return "smth"
        }
        set {
            // doing smth
        }
    }
}

@propertyWrapper struct Dashed {
    let value: String
    
    init(wrappedValue: String) {
        self.value = wrappedValue
    }
    
    var wrappedValue: String {
        get {
            return "smth"
        }
        set {
            // doing smth
        }
    }
}

class MyClass2 {
    // можно
    @Dashed var someString: String = "value"
    // можно
    @Trimmed var someString2: String = "value"
    // нельзя
//    @Dashed @Trimmed var someString3: String = "value"
}

//@State - Binding<Value>
//@Binding - Binding<Value>
//@ObservedObject - Binding<Value> (*)
//@EnvironmentObject - Binding<Value> (*)
//@Published - Publisher<Value, Never>

import SwiftUI

struct MyView: View {
    @State var state = 1
    @Binding(get: { return "smth" }, set: { _ in /* doing smth */ }) var binding: String
    @ObservedObject var observedObject = ViewState()
    @Environment(\.horizontalSizeClass) var horizontalSizeClass
    @EnvironmentObject var environmentObject: ViewState
    @FetchRequest var someProp
    
    init() {
        
    }
    
    var body: some View {
        return Text("Hello world!")
    }
}

class ViewState: ObservableObject {
    
}