ResizableSheet

ResizableSheeet is a half modal view library for SwiftUI.
You can easily implement a half modal view.

Target

Swift5.5
iOS14+

Installation

Only SwiftPM

Features

3 states are supported.
- hidden
- medium
- large
The medium size is automatically calculated baesd on the content.
You can update view for each state.
ResizableSheet contains ResizableScrollView and TrackableScrollView.
TrackableScrollView is a wrapper view of UIScrollView and the offset synchronizes with dragging of sheet.
ResizableScroolView is a wrapper class of TrackableScrollView, and
ResizableSheet can be shonw on another ResizableSheet.

Simple Example

To use ResizableSheet, follow these steps.

Create ResizableSheetCenter and embed it to your view in your root view like RootView.

struct RootView: View { 
    let windowScene: UIWindowScene?

    var resizableSheetCenter: ResizableSheetCenter? {
        windowScene.flatMap(ResizableSheetCenter.resolve(for:))
    }
    
    var body: some View { 
        YOUR_VIEW
            .environment(\.resizableSheetCenter, resizableSheetCenter)
    }
}

Prepare ResizableSheetState with @State, and call resizableSheet.
You can customize the resizableSheet by chaining some methods.

struct SomeView: View {

    @State var state: ResizableSheetState = .hidden

    var body: some View {
        Button("Show sheet") {
            state = .medium
        }
        .resizableSheet($state) { builder in
            builder.content { context in
                Text("text")
                    .padding()
            }
        }
    }
}

That’s all!
You can show a half modal view by tapping the button “Show sheet”, and you can expand or remove the sheet by dragging it.

View structure

ResizableSheet has some view components.
You can control each view components based on current status.

ResizableSheet
 └─ background
     ├─ outside
     └─ sheet background
         └─ content

Example

Complex Layout

You can update the view based on the current status.
The argument context has some informatios about the sheet, like state, view size, progress of dragging and diffY.

Based on the context, you can update the content.
Tips: Don’t forget to add .allowsHitTesting(false) to Color view. If you don’t add it, the dragging gesture is not recognized.

view.resizableSheet($state) { builder in
    builder.content { context in
        VStack {
            Text(context.state == .hidden ? "hidden" :
                    context.state == .medium ? "medium" : "large"
            )
            Color.gray
                .frame(height:
                        context.state == .medium ? max(0, context.diffY) :
                        context.state == .hidden ? 0 : nil
                )
                .opacity(context.state == .medium ? context.progress : 1.0 - abs(context.progress))
                .allowsHitTesting(false)
            Text("Buttom")
        }
        .padding()
    }
}

Supported status

ResizableSheet supports 3 statuses, .hidden, .medium and .large.
In default setting, the all statuses are supported, but you can stop to support any statuses.

view.resizableSheet($state) { builder in
    builder.content { context in
        Text("Text").frame(height: 300)
    }
    .supportedState([.medium])
}

Multi Sheets

ResizableSheet supports multiple sheets.
By adding id, ResizableSheet can show multiple sheets.

struct SomeSheet: View {

    @State var stateA: ResizableSheetState = .hidden
    @State var stateB: ResizableSheetState = .hidden

    var body: some View {
        Button("Show sheet A") {
            stateA = .medium
        }
        .resizableSheet($stateA, id: "A") { builder in
            builder.content { context in
                Button("Show sheet B") {
                    stateB = .medium
                }.frame(height: 300)
            }
        }
        .resizableSheet($stateB, id: "B") { builder in
            builder.content { context in
                Button("remove all sheet") {
                    stateA = .hidden
                    stateB = .hidden
                }.frame(height: 200)
            }
        }
    }
}

ResizableScroolView (TrackableScrollView)

ResizableSheet includes ResizableScrollView.
The view synchronises the offset with ResizableSheet.
Tips: Using ResizableScroolView is recommended because you don’t need to calculate the medium size.

view.resizableSheet($state) { builder in
    builder.content { context in
        ResizableScrollView(context: context) {
            // These views are shown in medium size and large size.
            ForEach(0..<5) { index in
                Text("\(index)")
                    .padding()
            }
        } additional: {
            // These views are shown in only large size.
            ForEach(5..<100) { index in
                Text("\(index)")
                    .padding()
            }
        }
    }
}

EmptyBackground

By passing EmptyView as background, user can control both the parent view and the sheet.

struct SomeView: View {
    @State var counter = 0
    @State var state: ResizableSheetState = .hidden
    var body: some View {
        VStack {
            Text("\(counter)")
                .font(.largeTitle)
            Button("count") {
                counter += 1
            }
            Spacer()
            Button("Show sheet") {
                state = .medium
            }
            Spacer()
        }
        .resizableSheet($state) { builder in
            builder.content { context in
                Content(counter: $counter).frame(height: 300)
            }
            .background { _ in EmptyView() } // add this line
        }
    }

    struct Content: View {
        @Binding var counter: Int
        var body: some View {
            VStack {
                Spacer()
                Text("\(counter)")
                    .font(.largeTitle)
                Button("reset") {
                    counter = 0
                }
                Spacer()
            }
        }
    }
}

GitHub

https://github.com/mtj0928/ResizableSheet