swift

Issue #838 We can write our custom Binding import SwiftUI extension Binding where Value == Date? { func flatten(defaultValue: Date) -> Binding<Date> { Binding<Date>( get: { wrappedValue ?? defaultValue }, set: { wrappedValue = $0 } ) } } Then use in places where it needs Binding with non-optional value DatePicker( "", selection: $date.flatten(defaultValue: Date()), displayedComponents: .hourAndMinute ) .datePickerStyle(WheelDatePickerStyle())

Issue #837 I usually use GeometryReader in background to get size of view, and encapsulate it inside a ViewModifier struct GetHeightModifier: ViewModifier { @Binding var height: CGFloat func body(content: Content) -> some View { content.background( GeometryReader { geo -> Color in DispatchQueue.main.async { height = geo.size.height } return Color.clear } ) } } This is useful to constrain NavigationView height when in use inside a bottom sheet struct FilterView: View { @State private var height: CGFloat = 0 var body: some View { BottomSheet { NavigationView { VStack { Text("content") } ....

Issue #836 If we have a Picker inside a View that has DragGesture, chances are when we scroll the wheel, the DragGesture is detected too To prevent this, we can attach a dummy DragGesture to our Picker Picker("", selection: $number) { ForEach(FavoriteNumbers.allCases) { number in Text(number.name) } } .pickerStyle(WheelPickerStyle()) .gesture(DragGesture())

Issue #835 I usually define ButtonStyle to encapsulate common styles related to buttons. Here we specify .frame(maxWidth: .infinity) to let this button take the whole width as possible struct MyActionButtonStyle: ButtonStyle { func makeBody(configuration: Configuration) -> some View { configuration.label .font(.headline.bold()) .foregroundColor(.white) .frame(height: 44) .frame(maxWidth: .infinity) .background(Color.green) .cornerRadius(8) } } If we have 2 buttons both specifying maxWidth: .infinity then they will be divided equally with a spacing specified by our HStack...

Issue #834 In iOS 15, we can use UISheetPresentationController to show bottom sheet like native Maps app. But before that there’s no such built in bottom sheet in UIKit or SwiftUI. We can start defining API for it. There are 3 ways to show overlay content in SwiftUI fullScreenCover: this presents like a modal view controller bottom up offset: initially hide our bottom sheet overlay: show overlay full screen so we can have custom control....

Issue #833 Use RelativeDateTimeFormatter. This assumes US locale is used extension Date { private static let relativeFormatter: RelativeDateTimeFormatter = { let formatter = RelativeDateTimeFormatter() formatter.calendar = Calendar(identifier: .gregorian) formatter.calendar?.locale = Locale(identifier: "en_US_POSIX") formatter.dateTimeStyle = .numeric formatter.unitsStyle = .abbreviated return formatter }() var ago: String { guard abs(timeIntervalSinceNow) > 60 else { return "Just Now" } let text = Self.relativeFormatter.localizedString(for: self, relativeTo: Date()) return text .replacingOccurrences(of: "ago", with: "") .replacingOccurrences(of: "min", with: "m") ....

Issue #831 We can normally listen to sub ObservableObject by either listen to its objectWillChange or its Publisher class SubModel: ObservableObject { @Published var count = 0 } class AppModel: ObservableObject { @Published var submodel: SubModel = SubModel() private var bag = Set<AnyCancellable>() init() { submodel.$count .sink(receiveValue: { [weak self] _ in self?.objectWillChange.send() }) } } We can then make a convenient extension to ease this. We use DispatchQueue to trigger objectWillChange in another run loop, to achieve didSet behavior...

Issue #829 Use PreferenceKey with a custom coordinateSpace to make our own TrackableScrollView. Note that the offset here is in reversed to contentOffset in normal UIScrollView import SwiftUI struct TrackableScrollView<Content: View>: View { @ViewBuilder let content: (ScrollViewProxy) -> Content let onContentSizeChange: (CGSize) -> Void let onOffsetChange: (CGPoint) -> Void var body: some View { ScrollViewReader { reader in ScrollView(showsIndicators: false) { GeometryReader { geo in Color.clear.preference( key: ScrollOffsetKey.self, value: geo.frame(in: ....

Issue #828 From iOS 15, FocusState Use focused(_:) for single TextField, and focused(_:equals:) for multiple TextField struct FormView: View { @FocusState private var isFocused: Bool @State private var name = "" var body: some View { TextField("Name", text: $name) .focused($isFocused) } } struct FormView: View { enum Field: Hashable { case usernameField case passwordField } @State private var username = "" @State private var password = "" @FocusState private var focusedField: Field?...

Issue #827 I’m trying a simple Future and sink. As long as I have debounce, only receiveCompletion gets called, but not receiveValue private var bag = Set<AnyCancellable>() let future = Future<Int, Never> { promise in promise(.success(1)) } future .debounce(for: .seconds(0.5), scheduler: DispatchQueue.main) .sink( receiveCompletion: { print($0) // Called }, receiveValue: { print($0) // Not called } ) .store(in: &bag) Reading debounce Publishes elements only after a specified time interval elapses between events....

Issue #826 Use isActive binding @State private var goesToDetail: Bool = false NavigationLink( destination: DetailView(viewModel: viewModel), isActive: $goesToDetail) { Button(action: { goesToDetail = true }) { Text("Next") } .buttonStyle(MyButtonStyle)) } We can also apply buttonStyle onto NavigationLink NavigationLink { FavoritesView() } label: { Image(systemImage: "star.fill") } .buttonStyle(MyButtonStyle())

Issue #825 For many apps that require user authentication, a common practice is to define a shared UserManager with an optional User. This is convenient but it requires us to constantly unwrap and check that user class UserManager { static let shared = UserManager() private(set) var user: User? } A more safer approach is to leverage Swift type system and separate the need based on authenticated and unauthenticated usage. For example, for an unauthorized users, we show the login screen....

Issue #824 Use a custom NavigationLink with EmptyView as the background, this failable initializer accepts Binding of optional value. This works well as the destination are made lazily. extension NavigationLink where Label == EmptyView { init?<Value>( _ binding: Binding<Value?>, @ViewBuilder destination: (Value) -> Destination ) { guard let value = binding.wrappedValue else { return nil } let isActive = Binding( get: { true }, set: { newValue in if !newValue { binding....

Issue #823 Make atomic components and compose them. Firstly with NavigationBar that has custom leading and trailing content, there we can customize padding. import SwiftUI struct NavigationBar<Leading: View, Trailing: View>: View { @ViewBuilder let leading: Leading @ViewBuilder let trailing: Trailing var body: some View { HStack { leading Spacer() trailing } .padding(.horizontal, 8) } } struct NavigationBarWithBackButton: View { let onBack: () -> Void var body: some View { NavigationBar( leading: backButton, trailing: EmptyView....

Issue #822 Get active screen with mouse func activeScreen() -> NSScreen? { let mouseLocation = NSEvent.mouseLocation let screens = NSScreen.screens let screenWithMouse = (screens.first { NSMouseInRect(mouseLocation, $0.frame, false) }) return screenWithMouse } Reposition our NSWIndow if window.frame != screen.frame { window.setFrameOrigin(screen.frame.origin) window.setContentSize(screen.frame.size) } Flip y as AppKit has coordinate origin starting from bottom left of the screen, while our SwiftUI starts from top left var point = window.convertPoint(fromScreen: event.locationInWindow) point.y = window....

Issue #821 Suppose we have a 16:9 preview Image and we want the title Text to be the same width First we need PreferenceKey to store and sync size struct SizePreferenceKey: PreferenceKey { typealias Value = CGSize static var defaultValue: Value = .zero static func reduce(value: inout Value, nextValue: () -> Value) { value = nextValue() } } For our Image, we use a GeometryReader in the background with invisible View Color....

Issue #819 Either use EasyStash or make a simple CodableImage struct CodableImage: Codable { let image: UIImage? init(image: UIImage) { self.image = image } enum CodingKeys: CodingKey { case data case scale } public init(from decoder: Decoder) throws { let container = try decoder.container(keyedBy: CodingKeys.self) let scale = try container.decode(CGFloat.self, forKey: .scale) let data = try container.decode(Data.self, forKey: .data) self.image = UIImage(data: data, scale: scale) } public func encode(to encoder: Encoder) throws { var container = encoder....

Issue #818 There’s a lot to do to imitate iOS ContextMenu look and feel vibrancy blur background haptics feedback targeted view position interaction dismiss gesture For now here’s a rough implementation of a custom context menu where we can show using .overlay import SwiftUI struct CustomContextMenu<Content: View>: View { @Binding var shows: Bool @ViewBuilder let content: Content var body: some View { ZStack { Color.black.opacity(0.1) .onTapGesture { shows = false } VStack(alignment: ....

Issue #817 Thanks to resultBuilder and container type in Swift, the following are possible in SwiftUI Local variable struct ChartView { var body: some View { computation } @ViewBuilder var computation: some View { let left = 10 let right = 20 if left + right == 30 { Text("Correct") } } } if and switch statement struct ChartView: View { @State private var showsOverlay: Bool = false @State private var overlayKind: OverlayKind?...

Issue #816 SwiftUI supports Menu but the menu items only appear after the menu button is touched. We can initiate the look and feel of Menu with a custom implementation import SwiftUI struct CustomMenu<Content: View>: View { @ViewBuilder let content: Content var body: some View { VStack(spacing: 0) { content } .frame(width: 234) .background( Color(UIColor.systemBackground) .opacity(0.8) .blur(radius: 50) ) .cornerRadius(14) } } struct CustomMenuButtonStyle: ButtonStyle { let symbol: String let color: Color func makeBody(configuration: Configuration) -> some View { HStack { configuration....