Created
January 13, 2020 08:38
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POC Navigator, driven by ObservableObject
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import SwiftUI | |
class NavState: ObservableObject { | |
@Published var modalActive = false | |
@Published var navDepth = 0 | |
} | |
struct ContentView: View { | |
@EnvironmentObject var navState: NavState | |
var body: some View { | |
GeometryReader { gr in | |
ZStack(alignment: .top) { | |
Page(width: gr.size.width, height: gr.size.height, depth: self.navState.navDepth) { | |
VStack(spacing: 10) { | |
Spacer() | |
Text("Hello, World! \(gr.size.width) \(gr.size.height)") | |
Button(action: { | |
self.navState.modalActive.toggle() | |
}) { | |
Text("Show modal") | |
} | |
Button(action: { | |
self.navState.navDepth = -1 | |
}) { | |
Text("Go to next page") | |
} | |
Button(action: { | |
self.navState.navDepth = -2 | |
}) { | |
Text("Go to third page") | |
} | |
Spacer() | |
} | |
} | |
Page(width: gr.size.width, height: gr.size.height, depth: self.navState.navDepth + 1) { | |
VStack(spacing: 10) { | |
Text("Hello, World again \(gr.safeAreaInsets.top)") | |
Button(action: { | |
self.navState.modalActive.toggle() | |
}) { | |
Text("Show modal") | |
} | |
Button(action: { | |
self.navState.navDepth = -2 | |
}) { | |
Text("Go to third page") | |
} | |
Button(action: { | |
self.navState.navDepth = 0 | |
}) { | |
Text("Go back") | |
} | |
Spacer() | |
}.frame(width: gr.size.width, height: gr.size.height - gr.safeAreaInsets.top) | |
.background(Color.orange) | |
.offset(CGSize(width: 0, height: gr.safeAreaInsets.top)) | |
} | |
Page(width: gr.size.width, height: gr.size.height, depth: self.navState.navDepth + 2) { | |
VStack(spacing: 10) { | |
Text("Hello, World again \(gr.safeAreaInsets.top)") | |
Button(action: { | |
self.navState.modalActive.toggle() | |
}) { | |
Text("Show modal") | |
} | |
Button(action: { | |
self.navState.navDepth = -1 | |
}) { | |
Text("Go back One") | |
} | |
Button(action: { | |
self.navState.navDepth = 0 | |
}) { | |
Text("Go back") | |
} | |
Spacer() | |
}.frame(width: gr.size.width, height: gr.size.height - gr.safeAreaInsets.top) | |
.background(Color.green) | |
.offset(CGSize(width: 0, height: gr.safeAreaInsets.top)) | |
} | |
VStack { | |
Text("Modal") | |
Button(action: { | |
self.navState.modalActive.toggle() | |
}) { | |
Text("Dismiss") | |
} | |
}.frame(width: gr.size.width, height: gr.size.height - 120) | |
.background(Color.yellow) | |
.offset(CGSize(width: 0, height: self.navState.modalActive ? 120 : gr.size.height)) | |
} | |
}.edgesIgnoringSafeArea(.all).animation(.easeInOut) | |
} | |
} | |
struct Page<Content: View>: View { | |
var width: CGFloat | |
var height: CGFloat | |
var depth: Int | |
var content: () -> Content | |
init(width: CGFloat, height: CGFloat, depth: Int, @ViewBuilder content: @escaping () -> Content) { | |
self.width = width | |
self.height = height | |
self.depth = depth | |
self.content = content | |
} | |
var body: some View { | |
VStack { | |
self.content() | |
}.frame(width: width, height: height) | |
.offset(CGSize(width: CGFloat(depth) * width, height: 0)) | |
} | |
} | |
struct ContentView_Previews: PreviewProvider { | |
static var previews: some View { | |
ContentView().environmentObject(NavState()) | |
} | |
} |
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Navigation on iOS in SwiftUI is buggy, confusing and on reflection actually pretty poorly aligned with how we'd probably want to do it in a reactive/SwiftUI world. See e.g. https://stackoverflow.com/questions/58404725/why-does-my-swiftui-app-crash-when-navigating-backwards-after-placing-a-navigat/58666951#58666951 for how Apple have broken it in different ways in each recent SwiftUI update!
So how hard would it be to create a fully custom, nicely animated navigator?