React Native 三:样式

index.android.js文件
import React, {
    … …
} from ‘react-native‘;
class AwesomeProject extends Component {
  render() {
    return (
      <View>
            //全部核心组件都能够接受style属性
           <Text style={styles.base}>Declare Style</Text>
            //接受数组形式的多个style
           <Text style={[styles.base, styles.background]}>Declare Style</Text>
            //依据某些条件选择性的加入样式。否定型取值如false，undefined和null则会被忽略
            <View style={[styles.base, true && styles.active]}/>
            //能够在render方法中创建样式，多个值冲突的时候，右边的元素优先级最高
            <View style={[styles.background, styles.base, { width:80, height:80}]}/>
       </View>
    );
  }
}
//声明样式
var styles = StyleSheet.create({
  base: {
    width: 100,
    height: 38,
  },
  background: {
    backgroundColor: ‘#cccccc‘,
  },
  active: {
    borderWidth: 2,
    borderColor: ‘#00ff00‘,
  },
});
AppRegistry.registerComponent(‘AwesomeProject‘, () => AwesomeProject);

 index.android.js文件：
     import React, {
         … …   
     } from ‘react-native‘;
     class AwesomeProject extends Component {
         render() {
              return (
                   <View style={styles.flexcontain}>
                       <View style={styles.flexitem}>
                         <Text>1</Text>
                       </View>
                       <View style={styles.flexitem}>
                         <Text>2</Text>
                       </View>
                       <View style={styles.flexitem}>
                         <Text>3</Text>
                       </View>
                       <View style={styles.flexitem}>
                         <Text>4</Text>
                       </View>
                       <View style={[styles.flexitem,styles.item5]}>
                         <Text>5</Text>
                       </View>
                </View>
              );
            }
     }
     var styles = StyleSheet.create({
          flexcontain: {
               width:300,
              height:300,
              borderWidth:1,
              borderColor:‘blue‘,
              flexDirection:‘row‘,
              top:100,
              left:100,
         },
         flexitem: {
              width:50,
              height:50,
              borderWidth:1,
              borderColor:‘white‘,
              backgroundColor:‘gray‘,
              justifyContent:‘center‘,
              alignItems:‘center‘,
       },
       item5: {
         alignSelf:‘stretch‘,
       },
     });
     AppRegistry.registerComponent(‘AwesomeProject‘, () => AwesomeProject);

import React, {
  AppRegistry,
  … … 
} from ‘react-native‘;

//创建List组件
var List = React.createClass({
  //声明传递參数和參数类型
  propTypes: {
    style: View.propTypes.style,
    elementStyle: View.propTypes.style,
  },
  render() {
    var elements = [‘element1‘,‘element2‘,‘element3‘];
    return (
        //使用參数传递过来的样式设置子组件
        <View style={this.props.style}>
          //直接调用和使用參数传递的样式设置子组件
          {elements.map((element) =><View key={element} style={[styles.element, this.props.elementStyle]} />)}
        </View>
    );
  }
});

class AwesomeProject extends Component {
  render() {
    return (
      <View>
        <List style={styles.list} elementStyle={styles.listElement} />
      </View>
    );
  }
}

var styles = StyleSheet.create({
  //传递给子组件样式list
  list: {
    width:300,
    height:300,
    borderWidth:1,
    borderColor:‘blue‘,
  },
  //传递给子组件样式listElement
  listElement: {
    width:50,
    height:50,
    backgroundColor:‘gray‘,
  },
  //直接调用样式element
  element: {
    borderWidth:1,
    borderColor:‘yellow‘,
  }
});
AppRegistry.registerComponent(‘AwesomeProject‘, () => AwesomeProject

提示1：假设RoadJS的时候，页面报错例如以下：
Warning: Each child in an array or iterator should have a 
unique "key" prop. Check the render method of List.
处理1：在map函数中的<View>加上key={element}属性；