a part of image in dataSource not appear in iOS. 部分图片在iOS上无法显示。

Which OS ?

iOS

Version

Which versions are you using:

• react-native-swiper v?
  1.5.13
• react-native v0.?.?
  0.57.0

Expected behaviour

in iOS：
if dataSource length is 6, the swiper works 4th、5th、6th images is no problem, but the 1st 2ed 3rd image not appear.
in Android is not problem.

Actual behaviour

iOS加载网络图片，前三张出不来，第一张出来的时候0.5秒就闪过了，然后第二张、第三张就出不来。
Android正常。

How to reproduce it>

To help us, please fork this component, modify one example in examples folder to reproduce your issue and include link here.

render() {
const swiperItems = this.props.dataSource.map(item => {
return (
<Image
source={{uri:constants.SDD_PIC_URL + (this.props.isGoodsDetail ? item : item.pic_id)}}
style={{width: width, height: 100}}
key={item.position}
/>
)
});
return (

{swiperItems}

        </Swiper>
    );
}

Steps to reproduce

in iOS：
if dataSource length is 6, the swiper works 4th、5th、6th images is no problem, but the 1st 2ed 3rd image not appear.
in Android is not problem.

Begin in the examples folder and reproduce the six-image autoplay case on iOS using the shown Swiper props and network Image sources. Compare the first three images with images 4–6 and with Android behavior; done means all six images display reliably on iOS without the initial flash.