Add Apple Sign In

example/lib/main.dart

@@ -15,12 +15,14 @@ class MyApp extends StatelessWidget {
           title: Text("flutter_auth_buttons"),
         ),
         backgroundColor: Color.fromARGB(0xFF, 0xF0, 0xF0, 0xF0),
-        body: Center(
+        body: SingleChildScrollView(
           child: Column(
             children: <Widget>[
               Heading("Natural size"),
               Column(
                 children: <Widget>[
+                  AppleSignInButton(onPressed: () {}),
+                  AppleSignInButton(onPressed: () {}, darkMode: true),
                   GoogleSignInButton(onPressed: () {}),
                   GoogleSignInButton(onPressed: () {}, darkMode: true),
                   FacebookSignInButton(onPressed: () {}),
@@ -36,6 +38,8 @@ class MyApp extends StatelessWidget {
                 child: Column(
                   crossAxisAlignment: CrossAxisAlignment.stretch,
                   children: <Widget>[
+                    AppleSignInButton(onPressed: () {}),
+                    AppleSignInButton(onPressed: () {}, darkMode: true),
                     GoogleSignInButton(onPressed: () {}),
                     GoogleSignInButton(onPressed: () {}, darkMode: true),
                     FacebookSignInButton(onPressed: () {}),

lib/flutter_auth_buttons.dart

@@ -2,3 +2,4 @@ export 'src/facebook.dart';
 export 'src/google.dart';
 export 'src/microsoft.dart';
 export 'src/twitter.dart';
+export 'src/apple.dart';

lib/src/apple.dart

@@ -0,0 +1,76 @@
+import 'package:flutter/material.dart';
+import 'package:flutter_auth_buttons/src/button.dart';
+
+const double defaultBorderRadius = 3.0;
+
+/// A sign in button that matches Apple's design guidelines.
+class AppleSignInButton extends StatelessWidget {
+  final String text;
+  final bool darkMode;
+  final double borderRadius;
+  final VoidCallback onPressed;
+
+  /// Creates a new button. Set [darkMode] to `true` to use the dark
+  /// black background variant with white text, otherwise an all-white background
+  /// with dark text is used.
+  AppleSignInButton(
+      {this.onPressed,
+      // 'Continue with Apple' is also an available variant depdening on App's sign-in experience.
+      this.text = 'Sign in with Apple',
+      this.darkMode = false,
+      // Apple doesn't specify a border radius, but this looks about right.
+      this.borderRadius = defaultBorderRadius,
+      Key key})
+      : assert(text != null),
+        super(key: key);
+
+  @override
+  Widget build(BuildContext context) {
+    return StretchableButton(
+      buttonColor: darkMode ? Colors.black : Colors.white,
+      borderRadius: borderRadius,
+      onPressed: onPressed,
+      buttonPadding: 0.0,
+      children: <Widget>[
+        Center(
+          child: Row(
+            children: <Widget>[
+              Padding(
+                padding: const EdgeInsets.only(left: 28.0),
+                child: Container(
+                  height: 38.0,
+                  width: 38.0,
+                  decoration: BoxDecoration(
+                    borderRadius: BorderRadius.circular(this.borderRadius),
+                  ),
+                  child: Center(
+                    child: Image(
+                      image: AssetImage(
+                        "graphics/apple_logo_${darkMode ? "white" : "black"}.png",
+                        package: "flutter_auth_buttons",
+                      ),
+                      height: 16.0,
+                      width: 16.0,
+                    ),
+                  ),
+                ),
+              ),
+              Padding(
+                padding: const EdgeInsets.fromLTRB(0.0, 12.0, 36.0, 8.0),
+                child: Text(
+                  text,
+                  style: TextStyle(
+                    fontSize: 15.0,
+                    fontFamily: "SF Pro",
+                    fontWeight: FontWeight.w500,
+                    color: darkMode ? Colors.white : Colors.black,
+                  ),
+                ),
+              ),
+            ],
+          ),
+        )
+      ],
+    );
+  }
+}

pubspec.yaml

@@ -22,9 +22,15 @@ flutter:
     - packages/flutter_auth_buttons/graphics/flogo-HexRBG-Wht-100.png
     - packages/flutter_auth_buttons/graphics/Twitter_Logo_Blue.png
     - packages/flutter_auth_buttons/graphics/ms-symbollockup_mssymbol_19.png
+    - packages/flutter_auth_buttons/graphics/apple_logo_black.png
+    - packages/flutter_auth_buttons/graphics/apple_logo_white.png
 
   fonts:
     - family: Roboto
       fonts:
         - asset: fonts/Roboto-Medium.ttf
+          weight: 500
+    - family: SF Pro
+      fonts:
+        - asset: fonts/SF-Pro-Medium.ttf
           weight: 500