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@mayoff
Created November 5, 2021 16:28
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demo code for laying out a SwiftUI table with fitted columns
import SwiftUI
fileprivate struct WidthPreferenceKey: PreferenceKey {
static var defaultValue: [AnyHashable: CGFloat] { [:] }
static func reduce(value: inout [AnyHashable : CGFloat], nextValue: () -> [AnyHashable : CGFloat]) {
value.merge(nextValue(), uniquingKeysWith: { max($0, $1) })
}
}
extension WidthPreferenceKey: EnvironmentKey { }
extension EnvironmentValues {
fileprivate var widthPreference: WidthPreferenceKey.Value {
get { self[WidthPreferenceKey.self] }
set { self[WidthPreferenceKey.self] = newValue }
}
}
extension View {
public func widthPreference<Domain: Hashable>(_ key: Domain) -> some View {
return self.modifier(WidthPreferenceModifier(key: key))
}
}
fileprivate struct WidthPreferenceModifier: ViewModifier {
@Environment(\.widthPreference) var widthPreference
var key: AnyHashable
func body(content: Content) -> some View {
content
.fixedSize(horizontal: true, vertical: false)
.background(GeometryReader { proxy in
Color.clear
.preference(key: WidthPreferenceKey.self, value: [key: proxy.size.width])
})
.frame(width: widthPreference[key])
}
}
public struct WidthPreferenceDomain<Content: View>: View {
@State private var widthPreference: WidthPreferenceKey.Value = [:]
private var content: Content
public init(@ViewBuilder content: () -> Content) {
self.content = content()
}
public var body: some View {
content
.environment(\.widthPreference, widthPreference)
.onPreferenceChange(WidthPreferenceKey.self) { widthPreference = $0 }
}
}
struct ContentView: View {
var body: some View {
VStack(spacing: 0) {
ZStack {
TitleBackground()
Text("Clients")
.foregroundColor(.white)
}
TableView()
Spacer()
}
}
}
enum ColumnId: Hashable {
case name
case balance
case currency
}
struct TableView: View {
var body: some View {
WidthPreferenceDomain {
VStack(spacing: 0) {
HStack(spacing: 30) {
Text("Name")
.widthPreference(ColumnId.name)
Text("Balance")
.widthPreference(ColumnId.balance)
Text("Currency")
.widthPreference(ColumnId.currency)
Spacer()
}
.frame(maxWidth:.infinity)
.padding(12)
.background(Color(#colorLiteral(red: 0.9332349896, green: 0.9333916306, blue: 0.9332130551, alpha: 1)))
ForEach(0 ..< 4) { _ in
RowView()
}
}
}
}
}
struct RowView : View {
var body: some View {
HStack(spacing: 30) {
Text("John")
.widthPreference(ColumnId.name)
Text("$5300")
.widthPreference(ColumnId.balance)
Text("EUR")
.widthPreference(ColumnId.currency)
Spacer()
}
.padding(12)
}
}
struct TitleBackground: View {
var body: some View {
ZStack(alignment: .bottom){
Rectangle()
.frame(maxWidth: .infinity, maxHeight: 60)
.foregroundColor(.red)
.cornerRadius(15)
//We only need the top corners rounded, so we embed another rectangle to the bottom.
Rectangle()
.frame(maxWidth: .infinity, maxHeight: 15)
.foregroundColor(.red)
}
}
}
struct ContentView_Previews: PreviewProvider {
static var previews: some View {
ContentView()
}
}
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