react native 中 ios默认是不能加载webp格式图片的，用了一个第三方库
1.npm install react-native-webp --save
2.rnpm link react-native-webp
3.Open your project in xcode
Right click your 找一个文件夹（） and select "Add Files to ..."（creat guoup方式）Select "WebP.framework" from node_modules/react-native-webp/ and click "OK"
Select your Target -> Select "Build Settings"
Add "$(SRCROOT)/../node_modules/react-native-webp" to the "Framework Search Path"
ok
2019.10.21补充：如果报错'RCTImageLoader.h' file not found，将DBAWebpImageDecoder.h文件#import "RCTImageLoader.h"改为#import <React/RCTImageLoader.h>
