Initialize partial sheet using binding (#67)

* PartialSheetAddModifier initial implementation

* Add onDismiss handling to the modifier

* Public modifier

* Rewritten ViewModifier, added example

* Added method comment

* Make update fields optional

* Update sheet content while shown

Co-authored-by: woko <[email protected]>

Author: woko666

Example/PartialSheetExample.xcodeproj/project.pbxproj

@@ -26,6 +26,7 @@
 		3B9841FC24E880870052A996 /* PickerExample.swift in Sources */ = {isa = PBXBuildFile; fileRef = 3B9841FA24E880870052A996 /* PickerExample.swift */; };
 		3B9841FD24E880870052A996 /* DatePickerExample.swift in Sources */ = {isa = PBXBuildFile; fileRef = 3B9841FB24E880870052A996 /* DatePickerExample.swift */; };
 		3BF874DF24E6F4DE004F4550 /* BlurredSheetExample.swift in Sources */ = {isa = PBXBuildFile; fileRef = 3BF874DE24E6F4DE004F4550 /* BlurredSheetExample.swift */; };
+		F8E410DE25015F710064D3A6 /* ViewModifierExample.swift in Sources */ = {isa = PBXBuildFile; fileRef = F8E410DD25015F710064D3A6 /* ViewModifierExample.swift */; };
 /* End PBXBuildFile section */
 
 /* Begin PBXFileReference section */
@@ -51,6 +52,7 @@
 		3B9841FA24E880870052A996 /* PickerExample.swift */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.swift; path = PickerExample.swift; sourceTree = "<group>"; };
 		3B9841FB24E880870052A996 /* DatePickerExample.swift */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.swift; path = DatePickerExample.swift; sourceTree = "<group>"; };
 		3BF874DE24E6F4DE004F4550 /* BlurredSheetExample.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = BlurredSheetExample.swift; sourceTree = "<group>"; };
+		F8E410DD25015F710064D3A6 /* ViewModifierExample.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = ViewModifierExample.swift; sourceTree = "<group>"; };
 /* End PBXFileReference section */
 
 /* Begin PBXFrameworksBuildPhase section */
@@ -74,6 +76,7 @@
 				01A013982458E4D800D0F5DD /* ListExample.swift */,
 				0174F416245962B80053C454 /* PushNavigationExample.swift */,
 				3BF874DE24E6F4DE004F4550 /* BlurredSheetExample.swift */,
+				F8E410DD25015F710064D3A6 /* ViewModifierExample.swift */,
 			);
 			path = Examples;
 			sourceTree = "<group>";
@@ -217,6 +220,7 @@
 				3B9841FD24E880870052A996 /* DatePickerExample.swift in Sources */,
 				0174F419245A569C0053C454 /* BlurEffectView.swift in Sources */,
 				1F177AA723E1F0E0006F59D0 /* DragState.swift in Sources */,
+				F8E410DE25015F710064D3A6 /* ViewModifierExample.swift in Sources */,
 				1F177AA623E1F0E0006F59D0 /* PartialSheetViewModifier.swift in Sources */,
 				01A013992458E4D800D0F5DD /* ListExample.swift in Sources */,
 				1F177A7023E1ECC3006F59D0 /* SceneDelegate.swift in Sources */,

Example/PartialSheetExample/ContentView.swift

@@ -65,6 +65,10 @@ struct ContentView: View {
                         destination: BlurredExample(),
                         label: {Text("Blurred Example")
                     })
+                    NavigationLink(
+                        destination: ViewModifierExample(),
+                        label: {Text("ViewModifier Example")
+                    })
                 }
                 Spacer()
                 Spacer()

Example/PartialSheetExample/Examples/ViewModifierExample.swift

@@ -0,0 +1,58 @@
+//
+//  ViewModifierExample.swift
+//  PartialSheetExample
+//
+//  Created by woko on 03/09/2020.
+//  Copyright © 2020 Swift. All rights reserved.
+//
+
+import SwiftUI
+
+struct ViewModifierExample: View {
+    @State var isSheetShown = false
+    @State var viewContent = "Initial content"
+    var body: some View {
+        HStack {
+            Spacer()
+            Button(action: {
+                self.isSheetShown = true
+            }, label: {
+                Text("Display the ViewModifier sheet")
+            })
+            .padding()
+            Spacer()
+        }
+        .navigationBarTitle("ViewModifier Example")
+        .navigationViewStyle(StackNavigationViewStyle())
+        .partialSheet(isPresented: $isSheetShown) {
+            ViewModifierView(content: self.$viewContent)
+                .padding(.vertical, 50)
+        }
+    }
+}
+
+struct ViewModifierExample_Previews: PreviewProvider {
+    static var previews: some View {
+        NavigationView {
+            ViewModifierExample()
+        }
+        .addPartialSheet()
+        .navigationViewStyle(StackNavigationViewStyle())
+        .environmentObject(PartialSheetManager())
+    }
+}
+
+struct ViewModifierView: View {
+    @Binding var content: String
+    
+    var body: some View {
+        VStack {
+            Text(content)
+            Button(action: {
+                self.content = "Inner content"
+            }, label: {
+                Text("Change content")
+            })
+        }
+    }
+}

Sources/PartialSheet/PartialSheetManager.swift

@@ -35,7 +35,7 @@ public class PartialSheetManager: ObservableObject {
         }
     }
     /// The content of the sheet
-    private(set) var content: AnyView
+    @Published private(set) var content: AnyView
     /// the onDismiss code runned when the partial sheet is closed
     private(set) var onDismiss: (() -> Void)?
 
@@ -54,6 +54,24 @@ public class PartialSheetManager: ObservableObject {
         self.isPresented = true
     }
 
+    /**
+     Updates some properties of the **Partial Sheet**
+    - parameter isPresented: If the partial sheet is presented
+    - parameter content: The content to place inside of the Partial Sheet.
+    - parameter onDismiss: This code will be runned when the sheet is dismissed.
+    */
+    public func updatePartialSheet<T>(isPresented: Bool? = nil, content: (() -> T)? = nil, onDismiss: (() -> Void)? = nil) where T: View {
+        if let content = content {
+            self.content = AnyView(content())
+        }
+        if let onDismiss = onDismiss {
+            self.onDismiss = onDismiss
+        }
+        if let isPresented = isPresented {
+            self.isPresented = isPresented
+        }
+    }
+
     /// Close the Partial Sheet and run the onDismiss function if it has been previously specified
     public func closePartialSheet() {
         self.isPresented = false

Sources/PartialSheet/PartialSheetViewModifier.swift

@@ -349,3 +349,42 @@ extension PartialSheet {
     }
 
 }
+
+struct PartialSheetAddView<Base: View, InnerContent: View>: View {
+    @EnvironmentObject var partialSheetManager: PartialSheetManager
+    
+    @Binding var isPresented: Bool
+    let content: () -> InnerContent
+    let base: Base
+    
+    @State var model = Model()
+
+    var body: some View {
+        if model.update(value: isPresented) {
+            DispatchQueue.main.async(execute: updateContent)
+        }
+        return base
+    }
+    
+    func updateContent() {
+        partialSheetManager.updatePartialSheet(isPresented: isPresented, content: content, onDismiss: {
+            self.isPresented = false
+        })
+    }
+    
+    // hack around .onChange not being available in iOS13
+    class Model {
+        private var savedValue: Bool?
+        func update(value: Bool) -> Bool {
+            guard value != savedValue else { return false }
+            savedValue = value
+            return true
+        }
+    }
+}
+
+public extension View {
+    func partialSheet<Content: View>(isPresented: Binding<Bool>, @ViewBuilder content: @escaping () -> Content) -> some View {
+        PartialSheetAddView(isPresented: isPresented, content: content, base: self)
+    }
+}