feat(Stepper): Add Stepper component. (#179)

* 添加React Native组件

* 添加React Native组件

* 添加React Native组件

* 添加 Stepper 步进器组件

* 删除样式文件

example/examples/src/routes.tsx

@@ -330,6 +330,14 @@ export const stackPageData: Routes[] = [
       description: '通告栏',
     },
   },
+  {
+    name: 'Stepper',
+    component: require('./routes/Stepper').default,
+    params: {
+      title: 'Stepper 步进器',
+      description: 'Stepper 步进器 用作增加或者减少当前数值。',
+    },
+  },
   {
     name: 'SpeedDial',
     component: require('./routes/SpeedDial').default,

example/examples/src/routes/Stepper/index.tsx

@@ -0,0 +1,63 @@
+/* tslint:disable:no-console */
+import React from 'react'
+import { View } from 'react-native'
+import {List, Stepper} from '@uiw/react-native';
+import Layout from '../../Layout';
+const {Header} = Layout;
+
+function onChange(value: any) {
+  console.log('changed', value)
+}
+
+export default class StepperExample extends React.Component<any, any> {
+
+  render() {
+    const {route} = this.props;
+    const description = route.params.description;
+    const title = route.params.title;
+
+    const readOnly = (
+      <Stepper
+        key="1"
+        max={999}
+        min={1}
+        readOnly={false}
+        defaultValue={888}
+        onChange={onChange}
+      />
+    )
+    return (
+      <View style={{ flex:1 }}>
+      <Header title={title} description={description} />
+        <List>
+          <List.Item
+            extra={
+              <Stepper
+                key="0"
+                max={9999}
+                min={0}
+                defaultValue={3}
+                onChange={onChange}
+              />
+            }>
+            请选择您要购买iPhone 12 的数量：
+          </List.Item>
+          <List.Item extra={readOnly}>您当前选择的数量为: </List.Item>
+          <List.Item
+            extra={
+              <Stepper
+                key="2"
+                disabled
+                max={100}
+                min={0}
+                defaultValue={0}
+                onChange={onChange}
+              />
+            }>
+            暂无库存：
+          </List.Item>
+        </List>
+      </View>
+    )
+  }
+}