feat: make the Liquid Glass effect opt-out via AlertStyle (#6)

The glass background (added for iOS/macOS 26) is now controllable through
a new `useGlassEffect` parameter on `AlertStyle.style(...)`:

- `nil` (default) / `true`: use Liquid Glass when running on iOS/macOS 26+
- `false`: always keep the classic solid-color / BlurView background

This lets apps whose design doesn't suit Liquid Glass opt out while
keeping glass on by default where available. Addresses the "I'd prefer
to have this be optional" feedback on elai950#112.

The new associated value defaults to nil, so existing `.style(...)`
call sites remain source-compatible. Also refreshed the README
AlertStyle reference (it was missing activityIndicatorColor too).

Co-authored-by: gambit1185_church <patrickmayo@churchofjesuschrist.org>
Co-authored-by: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

Author: 3 people

README.md

@@ -166,9 +166,13 @@ AlertStyle(backgroundColor: Color?,
             titleColor: Color?,
             subTitleColor: Color?,
             titleFont: Font?,
-            subTitleFont: Font?)
+            subTitleFont: Font?,
+            activityIndicatorColor: Color?,
+            useGlassEffect: Bool?)
 ```
 
+> **Liquid Glass:** on iOS 26 / macOS 26+ the toast background uses the native Liquid Glass material by default. To keep the classic solid-color / blur background, pass `useGlassEffect: false` in the style.
+
 #### Available Alert Types:
 - **Regular:** text only (Title and Subtitle).
 - **Complete:** animated checkmark.

Sources/AlertToast/AlertToast.swift

@@ -138,54 +138,65 @@ public struct AlertToast: View{
                    subTitleColor: Color? = nil,
                    titleFont: Font? = nil,
                    subTitleFont: Font? = nil,
-                   activityIndicatorColor: Color? = nil)
-        
+                   activityIndicatorColor: Color? = nil,
+                   useGlassEffect: Bool? = nil)
+
         ///Get background color
         var backgroundColor: Color? {
             switch self{
-            case .style(backgroundColor: let color, _, _, _, _, _):
+            case .style(backgroundColor: let color, _, _, _, _, _, _):
                 return color
             }
         }
-        
+
         /// Get title color
         var titleColor: Color? {
             switch self{
-            case .style(_,let color, _,_,_,_):
+            case .style(_,let color, _,_,_,_,_):
                 return color
             }
         }
-        
+
         /// Get subTitle color
         var subtitleColor: Color? {
             switch self{
-            case .style(_,_, let color, _,_,_):
+            case .style(_,_, let color, _,_,_,_):
                 return color
             }
         }
-        
+
         /// Get title font
         var titleFont: Font? {
             switch self {
-            case .style(_, _, _, titleFont: let font, _,_):
+            case .style(_, _, _, titleFont: let font, _,_,_):
                 return font
             }
         }
-        
+
         /// Get subTitle font
         var subTitleFont: Font? {
             switch self {
-            case .style(_, _, _, _, subTitleFont: let font,_):
+            case .style(_, _, _, _, subTitleFont: let font,_,_):
                 return font
             }
         }
 
         var activityIndicatorColor: Color? {
             switch self {
-            case .style(_, _, _, _, _, let color):
+            case .style(_, _, _, _, _, let color, _):
                 return color
             }
         }
+
+        /// Whether to use the Liquid Glass background on iOS/macOS 26+.
+        /// `nil` (the default) means glass is used when available; set `false`
+        /// to always keep the classic solid-color / blur background.
+        var useGlassEffect: Bool? {
+            switch self {
+            case .style(_, _, _, _, _, _, let useGlassEffect):
+                return useGlassEffect
+            }
+        }
     }
 
     ///The display mode
@@ -274,7 +285,7 @@ public struct AlertToast: View{
             .textColor(style?.titleColor ?? nil)
             .padding()
             .frame(maxWidth: 400, alignment: .leading)
-            .alertBackground(style?.backgroundColor ?? nil)
+            .alertBackground(style?.backgroundColor ?? nil, useGlassEffect: style?.useGlassEffect ?? true)
             .cornerRadius(10)
             .padding([.horizontal, .bottom])
         }
@@ -330,7 +341,7 @@ public struct AlertToast: View{
             .padding(.horizontal, 24)
             .padding(.vertical, 8)
             .frame(minHeight: 50)
-            .alertBackground(style?.backgroundColor ?? nil)
+            .alertBackground(style?.backgroundColor ?? nil, useGlassEffect: style?.useGlassEffect ?? true)
             .clipShape(Capsule())
             .overlay(Capsule().stroke(Color.gray.opacity(0.2), lineWidth: 1))
             .shadow(color: Color.black.opacity(0.1), radius: 5, x: 0, y: 6)
@@ -396,7 +407,7 @@ public struct AlertToast: View{
         }
         .padding()
         .withFrame(type != .regular && type != .loading)
-        .alertBackground(style?.backgroundColor ?? nil)
+        .alertBackground(style?.backgroundColor ?? nil, useGlassEffect: style?.useGlassEffect ?? true)
         .cornerRadius(10)
     }
 
@@ -637,12 +648,13 @@ fileprivate struct WithFrameModifier: ViewModifier{
 ///Fileprivate View Modifier to change the alert background
 @available(iOS 14, macOS 11, *)
 fileprivate struct BackgroundModifier: ViewModifier{
-    
+
     var color: Color?
-    
+    var useGlassEffect: Bool = true
+
     @ViewBuilder
     func body(content: Content) -> some View {
-        if #available(iOS 26, macOS 26, *) {
+        if #available(iOS 26, macOS 26, *), useGlassEffect {
             if let color = color {
                 content
                     .background(color)
@@ -744,8 +756,8 @@ public extension View{
     /// Choose the alert background
     /// - Parameter color: Some Color, if `nil` return `VisualEffectBlur`
     /// - Returns: some View
-    fileprivate func alertBackground(_ color: Color? = nil) -> some View{
-        modifier(BackgroundModifier(color: color))
+    fileprivate func alertBackground(_ color: Color? = nil, useGlassEffect: Bool = true) -> some View{
+        modifier(BackgroundModifier(color: color, useGlassEffect: useGlassEffect))
     }
 
     /// Choose the alert background