@capacitor/camera does not honor users selection order

Plugin(s)

@capacitor/camera

Capacitor Version

Latest Dependencies:

  @capacitor/cli: 5.5.1
  @capacitor/core: 5.5.1
  @capacitor/android: 5.5.1
  @capacitor/ios: 5.5.1

Installed Dependencies:

  @capacitor/cli: 5.2.2
  @capacitor/core: 5.2.2
  @capacitor/android: 5.2.2
  @capacitor/ios: 5.2.2

Platform(s)

iOS

Current Behavior

Method Camera.pickImages exposed by the @capacitor/camera plugin does not return image details using the same order in which users selected those images. Furthermore, selecting images over and over again, may yield different results each time (result of the pickImages is not stable from a sorting point of view).

In other words, if I have images 1 through 50, Camera.pickImages may return images in any arbitrary order. So, rolling with the same example as before, if I select images 1 through 50, I may get details about them in orders like:

• 1,2,3,4,...49,50 (if I'm very lucky)
• 2,1,3,4,7,10,5,....50,49
• or in any other permutation of those 50 numbers.

This is different from the behavior observed on Android where details about each image are returned using the same ordering in which user picked them. So, for example, in the first position of the array returned by the pickImages method, I'll find details about the firstly selected image. In the second position of that array, I'll find details of the second image selected by the user, and so on for each other image.

Same thing goes for the underlying <input type="file" multiple="multiple" /> we find in the web implementation of the @capacitor/camera plugin.

Expected Behavior

Expected result is that the order of selection is preserved, even when using the iOS implementation.
Additionally, selecting the same set of images multiple times, should yield to the same result.

Code Reproduction

const { photos } = await Camera.pickImages({
  quality: 100,
});

console.log(photos);

If the above snippet uses the web or Android implementations of the pickImages method, photos will be an array where each item is presented in the same order in which user selected images. If the above snippet uses the iOS implementation, photos may have different orders. This is especially true and evident when selecting many images (with 30 images you are pretty much certain to encounter this problem).

Additional Context

I did some debugging and it seems like the problem lies in the function picker defined in the CameraPlugin extension (file CameraPlugin.swift).
To be more precise, this problem boils down to a race condition in the handling of the result from self?.processedImage, where each processedImage is appended to an array in a closure of the asynchronous method loadObject.

We've already developed a patch for this problem and we can confirm that this solved the problem our users encountered.