feat: ability to handle badges. Refs onl1ner#21

Author: dkk

Example/Example/ContentView.swift

@@ -50,9 +50,23 @@ struct ContentView: View {
 
     @State private var selection: Item = .first
     @State private var visibility: TabBarVisibility = .visible
+    @State private var badgeNumberAtThird = 0
+    
+    private func badgeNumber(for tabItem: Item) -> Int? {
+        switch tabItem {
+        case Item.third:
+            return badgeNumberAtThird
+        default:
+            return nil
+        }
+    }
 
     var body: some View {
-        TabBar(selection: $selection, visibility: $visibility) {
+        TabBar(
+            selection: $selection,
+            visibility: $visibility,
+            badgeNumberForTabItem: badgeNumber(for:)
+        ) {
             Button {
                 withAnimation {
                     visibility.toggle()
@@ -65,8 +79,22 @@ struct ContentView: View {
             Text("Second")
                 .tabItem(for: Item.second)
 
-            Text("Third")
-                .tabItem(for: Item.third)
+            VStack(spacing: 40) {
+                Text("Third")
+                
+                Button {
+                    badgeNumberAtThird += 1
+                } label: {
+                    Text("Increase Badge Number")
+                }
+                
+                Button {
+                    badgeNumberAtThird = 0
+                } label: {
+                    Text("Reset Badge Number")
+                }
+            }
+            .tabItem(for: Item.third)
         }
         .tabBar(style: CustomTabBarStyle())
         .tabItem(style: CustomTabItemStyle())

Example/Example/Styles/TabItem/CustomTabItemStyle.swift

@@ -26,7 +26,7 @@ import TabBar
 
 struct CustomTabItemStyle: TabItemStyle {
 
-    public func tabItem(icon: String, title: String, isSelected: Bool) -> some View {
+    public func tabItem(icon: String, title: String, isSelected: Bool, badgeNumber: Int?) -> some View {
         ZStack {
             if isSelected {
                 Circle()
@@ -37,6 +37,18 @@ struct CustomTabItemStyle: TabItemStyle {
             Image(systemName: icon)
                 .foregroundColor(isSelected ? .white : Color("color.tab.item.foreground"))
                 .frame(width: 32.0, height: 32.0)
+            
+            if let badgeNumber = badgeNumber, badgeNumber > 0 {
+                Text("\(badgeNumber < 100 ? String(badgeNumber) : "99+")")
+                    .font(.callout)
+                    .foregroundColor(.white)
+                    .padding(.horizontal, 8)
+                    .background(
+                        Capsule()
+                            .foregroundColor(.red)
+                    )
+                    .offset(x: 26, y: -10)
+            }
         }
         .padding(.vertical, 8.0)
     }

Sources/TabBar/Common/Styles/TabItem/AnyTabItemStyle.swift

@@ -31,13 +31,13 @@ import SwiftUI
  to represent any item style.
  */
 public struct AnyTabItemStyle: TabItemStyle {
-    private let _makeTabItem: (String, String, String, Bool) -> AnyView
+    private let _makeTabItem: (String, String, String, Bool, Int?) -> AnyView
 
     public init<TabItem: TabItemStyle>(itemStyle: TabItem) {
-        self._makeTabItem = itemStyle.tabItemErased(icon:selectedIcon:title:isSelected:)
+        self._makeTabItem = itemStyle.tabItemErased(icon:selectedIcon:title:isSelected:badgeNumber:)
     }
 
-    public func tabItem(icon: String, selectedIcon: String, title: String, isSelected: Bool) -> some View {
-        return self._makeTabItem(icon, selectedIcon, title, isSelected)
+    public func tabItem(icon: String, selectedIcon: String, title: String, isSelected: Bool, badgeNumber: Int?) -> some View {
+        return self._makeTabItem(icon, selectedIcon, title, isSelected, badgeNumber)
     }
 }

Sources/TabBar/Common/Styles/TabItem/DefaultTabItem.swift

@@ -30,7 +30,7 @@ import SwiftUI
  items of `UITabBar` and used in `TabBar` by default.
  */
 public struct DefaultTabItemStyle: TabItemStyle {
-    public func tabItem(icon: String, selectedIcon: String, title: String, isSelected: Bool) -> some View {
+    public func tabItem(icon: String, selectedIcon: String, title: String, isSelected: Bool, badgeNumber: Int?) -> some View {
         VStack(spacing: 5.0) {
             Image(systemName: icon)
                 .renderingMode(.template)

Sources/TabBar/Common/Styles/TabItem/TabItemStyle.swift

@@ -33,20 +33,20 @@ import SwiftUI
 public protocol TabItemStyle {
     associatedtype Content : View
 
-    func tabItem(icon: String, title: String, isSelected: Bool) -> Content
-    func tabItem(icon: String, selectedIcon: String, title: String, isSelected: Bool) -> Content
+    func tabItem(icon: String, title: String, isSelected: Bool, badgeNumber: Int?) -> Content
+    func tabItem(icon: String, selectedIcon: String, title: String, isSelected: Bool, badgeNumber: Int?) -> Content
 }
 
 extension TabItemStyle {
-    public func tabItem(icon: String, title: String, isSelected: Bool) -> Content {
-        return self.tabItem(icon: icon, selectedIcon: icon, title: title, isSelected: isSelected)
+    public func tabItem(icon: String, title: String, isSelected: Bool, badgeNumber: Int?) -> Content {
+        return self.tabItem(icon: icon, selectedIcon: icon, title: title, isSelected: isSelected, badgeNumber: badgeNumber)
     }
 
-    public func tabItem(icon: String, selectedIcon: String, title: String, isSelected: Bool) -> Content {
-        return self.tabItem(icon: icon, title: title, isSelected: isSelected)
+    public func tabItem(icon: String, selectedIcon: String, title: String, isSelected: Bool, badgeNumber: Int?) -> Content {
+        return self.tabItem(icon: icon, title: title, isSelected: isSelected, badgeNumber: badgeNumber)
     }
 
-    func tabItemErased(icon: String, selectedIcon: String, title: String, isSelected: Bool) -> AnyView {
-        return .init(self.tabItem(icon: icon, selectedIcon: selectedIcon, title: title, isSelected: isSelected))
+    func tabItemErased(icon: String, selectedIcon: String, title: String, isSelected: Bool, badgeNumber: Int?) -> AnyView {
+        return .init(self.tabItem(icon: icon, selectedIcon: selectedIcon, title: title, isSelected: isSelected, badgeNumber: badgeNumber))
     }
 }

Sources/TabBar/View/TabBar.swift

@@ -52,6 +52,8 @@ public struct TabBar<TabItem: Tabbable, Content: View>: View {
     private var tabItemStyle : AnyTabItemStyle
     private var tabBarStyle  : AnyTabBarStyle
 
+    private var badgeNumberForTabItem: (TabItem) -> Int?
+    
     @State private var items: [TabItem]
 
     @Binding private var visibility: TabBarVisibility
@@ -67,11 +69,14 @@ public struct TabBar<TabItem: Tabbable, Content: View>: View {
     public init(
         selection: Binding<TabItem>,
         visibility: Binding<TabBarVisibility> = .constant(.visible),
+        badgeNumberForTabItem: @escaping (TabItem) -> Int? = { _ in nil },
         @ViewBuilder content: () -> Content
     ) {
         self.tabItemStyle = .init(itemStyle: DefaultTabItemStyle())
         self.tabBarStyle = .init(barStyle: DefaultTabBarStyle())
 
+        self.badgeNumberForTabItem = badgeNumberForTabItem
+        
         self.selectedItem = .init(selection: selection)
         self.content = content()
 
@@ -86,7 +91,8 @@ public struct TabBar<TabItem: Tabbable, Content: View>: View {
                     icon: item.icon,
                     selectedIcon: item.selectedIcon,
                     title: item.title,
-                    isSelected: self.selectedItem.selection == item
+                    isSelected: self.selectedItem.selection == item,
+                    badgeNumber: badgeNumberForTabItem(item)
                 )
                 .onTapGesture {
                     self.selectedItem.selection = item