[iOS] Webview source/uri cannot load base64 pdf

[ColinKrist]

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Environment

Run react-native info in your terminal and paste its contents here.
React Native Environment Info:
System:
OS: Windows 10
CPU: (8) x64 Intel(R) Core(TM) i7-7700T CPU @ 2.90GHz
Memory: 5.54 GB / 15.89 GB
Binaries:
Yarn: 1.10.1 - C:\Program Files (x86)\Yarn\bin\yarn.CMD
npm: 5.6.0 - C:\Program Files\nodejs\npm.CMD
IDEs:
Android Studio: Version 3.1.0.0 AI-173.4720617

Description

Describe your issue in detail. Include screenshots if needed. If this is a regression, let us know.

Prior to React Native 57+ Webview could load a base64 pdf on iOS since it was supported natively on UIWebview. After Expo recently upgraded to RN 57+ (Expo 31) our team hit this issue when using rn-pdf-reader-js since this library uses this functionality.

Usage

let data = "data:application/pdf;base64," + pdfbase64Data;

jsx:
<WebView
  style={{ flex: 1}}
  source={{ uri: data}}
/>

When loading the Webview we now get a promise rejection from resolveAssetSource().

NOTE: this image was taken from the expo forum post for rn-pdf-reader-js

NOTE: we haven't tried this with react-native-community/react-native-webview since it hasn't landed, but it seems that they have this working in their repository.

Reproducible Demo

Let us know how to reproduce the issue. Include a code sample, share a project, or share an app that reproduces the issue using https://snack.expo.io/. Please follow the guidelines for providing a MCVE: https://stackoverflow.com/help/mcve

[hramos]

Please use https://github.com/react-native-community/react-native-webview and file a bug there if you have issues.

[hughbe]

Anyone figured out a workaround?