[expo-gl] iOS app crash when using "capture" method

Expo SDK
1

Hello, I’m building app that take pictures.
User can edit those pictures and he can update brightness and contrast.

To build the app with React Native (without Expo) I am using these dependencies:

"gl-react": "4.0.1",
"gl-react-native": "4.0.1",
"react-native-unimodules": "^0.14.6",

I have a component called “BrightnessAndContrast”:

import React, { useRef, useState } from 'react'
import { Shaders, Node, GLSL } from 'gl-react'
import { Surface } from 'gl-react-native'

const shaders = Shaders.create({
  Saturate: {
    frag: GLSL`
  precision highp float;
  varying vec2 uv;
  uniform sampler2D t;
  uniform float contrast, saturation, brightness;
  const vec3 L = vec3(0.2125, 0.7154, 0.0721);
  void main() {
    vec4 c = texture2D(t, uv);
      vec3 brt = c.rgb * brightness;
      gl_FragColor = vec4(mix(
      vec3(0.5),
      mix(vec3(dot(brt, L)), brt, saturation),
      contrast), c.a);
  }`
  }
})

const Saturate = ({
  contrast,
  saturation,
  brightness,
  children
}) => (
  <Node
    shader={shaders.Saturate}
    uniforms={{ contrast, saturation, brightness, t: children }}
  />
)

const BrightnessAndContrast = ({ onSave, uri }) => {
  const surfaceRef = useRef<Surface>(null)
  const [contrast, setContrast] = useState(1)
  const [brightness, setBrightness] = useState(1)

  const handleOnSaveImage = async () => {
    try {
      const result = await surfaceRef.current?.glView.capture() // <-- this line crash on iOS
      onSave(result.uri)
    } catch (error) {
      console.log(error)
    }
  }

  return (
    <Container>
      <Surface ref={surfaceRef} style={{ width: 320, height: 320 }}>
        <Saturate {...{ brightness, contrast, saturation: 1}}>
          {{ uri }}
        </Saturate>
      </Surface>
      <Footer>
          {/* other code... */}
          <ButtonIcon
            onPress={handleOnSaveImage}
            renderIcon={() => <Check color='#FFF' />}
            text='Save'
          />
      </Footer>
    </Container>
  )
}

export { BrightnessAndContrast }

It works fine on Android, but on iOS, when I press “Save” and invoke the capture method, the app crashes with the following error:

2021-09-03 10:28:21.458968+0200 AwesomeApp[629:101590] *** Terminating app due to uncaught exception 'NSInvalidArgumentException', reason: '*** -[NSURL initFileURLWithPath:]: nil string parameter'
*** First throw call stack:
(0x1de90b180 0x1ddae39f8 0x1de8153a0 0x1df28a044 0x1df289fac 0x10077eefc 0x10077d8d4 0x10077da40 0x105f7b6f4 0x105f7cc78 0x105f84bf4 0x105f858b4 0x105f8f77c 0x1de52a114 0x1de52ccd4)
libc++abi.dylib: terminating with uncaught exception of type NSException
*** Terminating app due to uncaught exception 'NSInvalidArgumentException', reason: '*** -[NSURL initFileURLWithPath:]: nil string parameter'
terminating with uncaught exception of type NSException
(lldb)

After debugging I saw this method generateSnapshotPathWithExtension in EXGL/EXGLContext.m that give me error on line 285. This line return nil:

NSString *directory = [fileSystem.cachesDirectory stringByAppendingPathComponent:@"GLView"];

It works if I replace this string with

NSArray *paths = NSSearchPathForDirectoriesInDomains(NSCachesDirectory, NSUserDomainMask, YES);
  NSString *directory = [paths objectAtIndex:0];

Is this a known issue? Or am I missing something?

2

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