Refactoring / fixing

lib/widget/spinner.dart

@@ -0,0 +1,54 @@
+import 'package:flutter/material.dart';
+import 'package:flutter/cupertino.dart';
+
+import 'package:font_awesome_flutter/font_awesome_flutter.dart';
+
+class Spinner extends StatefulWidget {
+  final IconData icon;
+  final Duration duration;
+  final Color color;
+
+  const Spinner({
+    this.color = const Color.fromRGBO(150, 150, 150, 1),
+    Key key,
+    @required this.icon,
+    this.duration = const Duration(milliseconds: 1800),
+  }) : super(key: key);
+
+  @override
+  _SpinnerState createState() => _SpinnerState();
+}
+
+class _SpinnerState extends State<Spinner> with SingleTickerProviderStateMixin {
+  AnimationController _controller;
+  Widget _child;
+
+  @override
+  void initState() {
+    _controller = AnimationController(
+      vsync: this,
+      duration: Duration(milliseconds: 2000),
+    )
+      ..repeat();
+    _child = FaIcon(
+      widget.icon,
+      color: widget.color
+    );
+
+    super.initState();
+  }
+
+  @override
+  void dispose() {
+    _controller.dispose();
+    super.dispose();
+  }
+
+  @override
+  Widget build(BuildContext context) {
+    return RotationTransition(
+      turns: _controller,
+      child: _child,
+    );
+  }
+}