1、利用View绘制上、下三角

<View style={
{  width:0,height:0,borderTopWidth:12,borderRightWidth:12,borderBottomWidth:0,borderLeftColor:'transparent',borderTopColor:'#656565',borderRightColor:'transparent',borderBottomColor:'transparent',marginLeft:70}}>
</View>

2、利用View绘制左、右箭头

backIcon: {
    width: 14,height: 14,borderColor: '#777',borderLeftWidth: 2,borderBottomWidth: 2,transform: [{rotate: '45deg'}],backgroundColor: 'transparent',position: 'absolute',top: 33.9,left: 14.5
  }