Address PR comments

Author: bbrk24

Sources/SwiftCrossUI/Environment/EnvironmentValues.swift

@@ -45,14 +45,14 @@ public struct EnvironmentValues {
     var onResize: (_ newSize: ViewSize) -> Void
 
     // Backing storage for extensible subscript
-    private var extraKeys: [ObjectIdentifier: Any]
+    private var extraValues: [ObjectIdentifier: Any]
 
     public subscript<T: EnvironmentKey>(_ key: T.Type) -> T.Value {
         get {
-            extraKeys[ObjectIdentifier(T.self), default: T.defaultValue] as! T.Value
+            extraValues[ObjectIdentifier(T.self), default: T.defaultValue] as! T.Value
         }
         set {
-            extraKeys[ObjectIdentifier(T.self)] = newValue
+            extraValues[ObjectIdentifier(T.self)] = newValue
         }
     }
 
@@ -133,7 +133,7 @@ public struct EnvironmentValues {
         colorScheme = .light
         windowScaleFactor = 1
         window = nil
-        extraKeys = [:]
+        extraValues = [:]
     }
 
     /// Returns a copy of the environment with the specified property set to the
@@ -145,7 +145,7 @@ public struct EnvironmentValues {
     }
 }
 
-/// A key that can be used to extend the environment over the built-in values.
+/// A key that can be used to extend the environment with new properties.
 public protocol EnvironmentKey {
     /// The type of value the key can hold.
     associatedtype Value

Sources/UIKitBackend/KeyboardToolbar.swift

@@ -3,6 +3,11 @@ import UIKit
 
 /// An item which can be displayed in a keyboard toolbar. Implementers of this do not have
 /// to implement ``SwiftCrossUI/View``.
+///
+/// Toolbar items are expected to be "stateless". Mutations of `@State` properties of toolbar
+/// items will not cause the toolbar to be updated. The toolbar is only updated when the view
+/// containing the ``View/keyboardToolbar(animateChanges:body:)`` modifier is updated, so any
+/// state necessary for the toolbar should live in the view itself.
 public protocol ToolbarItem {
     /// Convert the item to a `UIBarButtonItem`, which will be placed in the keyboard toolbar.
     func asBarButtonItem() -> UIBarButtonItem
@@ -39,10 +44,6 @@ public enum ToolbarBuilder {
     public static func buildEither(second component: Component) -> Component {
         component
     }
-
-    public static func buildFinalResult(_ component: Component) -> [UIBarButtonItem] {
-        component.map { $0.asBarButtonItem() }
-    }
 }
 
 final class CallbackBarButtonItem: UIBarButtonItem {
@@ -80,9 +81,9 @@ extension Spacer: ToolbarItem {
         if let minLength, minLength > 0 {
             print(
                 """
-                Warning: Spacer's minLength is ignored inside keyboard toolbars, as \
-                flexible-length spacers cannot specify a minimum width. Use `.frame(width:)` \
-                for a fixed-length spacer.
+                Warning: Spacer's minLength property is ignored within keyboard toolbars \
+                due to UIKit limitations. Use `Spacer()` for unconstrained spacers and \
+                `Spacer().frame(width: _)` for fixed-length spacers.
                 """
             )
         }
@@ -168,11 +169,11 @@ extension View {
     ///   - body: The toolbar's contents
     public func keyboardToolbar(
         animateChanges: Bool = true,
-        @ToolbarBuilder body: @escaping () -> [UIBarButtonItem]
+        @ToolbarBuilder body: @escaping () -> ToolbarBuilder.Component
     ) -> some View {
         EnvironmentModifier(self) { environment in
             environment.with(\.updateToolbar) { toolbar in
-                toolbar.setItems(body(), animated: animateChanges)
+                toolbar.setItems(body().map { $0.asBarButtonItem() }, animated: animateChanges)
                 toolbar.sizeToFit()
             }
         }