mattyoung

import Foundation


struct SomeObject: Codable {
    let name: String
}

struct OtherObject: Codable {
    let number: Int
}

mattyoung

enum Color {
    case red
}

struct carsA {
    let ofColor: Color
}

let carsA = carsA(ofColor: .red)    // error: Circular reference

mattyoung

import SwiftUI

protocol Selectable: Identifiable {
    associatedtype Label : View
    var isSelected: Bool { get set }
    var label: Label { get }
}

struct Multiselect<T: Selectable>: View {
    @Binding var items: [T]

mattyoung

import SwiftUI

struct Child: View {
    @Binding var binding: Int

    var body: some View {
        VStack {
            Text("x = \(binding)")
            Button("Mutate parent view .x") {
                binding += 1    // this will cause a new child view push onto the nav stack

mattyoung

import SwiftUI

struct Child: View {
    @Binding var binding: Int

    var body: some View {
        VStack {
            Text("x = \(binding)")
            Button("Mutate parent view .x") {
                binding += 1    // this will cause various different nav stack push pop problem

mattyoung

import SwiftUI

struct ContentView: View {
    @AppStorage("number") var number = 1

    var body: some View {
        VStack {
            Text("Hello, world! number = \(number)")
                .padding()
            Button("+1") {

mattyoung

import SwiftUI

/// Wraps a view to be loaded on-demand when using a `NavigationLink`
/// This helps to increate performance as less of the graph is loaded initially.
struct NavigationLazyView<Content: View>: View {
    let build: () -> Content
    // as-is, compile error at call site
    init(_ build: @autoclosure @escaping () -> Content) {
    // !!! had to mark as @ViewBuilder here
//    init(@ViewBuilder _ build: /*@autoclosure*/ @escaping () -> Content) {

mattyoung

extension View {
    /// Workaround .foregroundColor(nil) not inherit from outter view bug
    ///
    /// ```
    /// ZStack {
    ///     Image(systemName: "star.fill")
    ///         .conditional(foregroundColor: Int.random(in: 1...5) < 2 ? .green : nil)
    /// }
    /// .foregroundColor(.red)
    /// ```

mattyoung

import SwiftUI

public protocol ObservablePropertySource: ObservableObject {
    static var shared: Self { get }
}

@propertyWrapper
public struct ObservableProperty<S: ObservablePropertySource, T>: DynamicProperty {
    @ObservedObject private var source: S

mattyoung

import SwiftUI

private struct OnFirstAppear: ViewModifier {
    let perform: () -> Void

    @State private var firstTime = true

    func body(content: Content) -> some View {
        content.onAppear {
            if firstTime {