fix(image-loader): use tempDirectory on iOS

[swiftyone]

The tempDirectory can be accessed from the WKWebView as well; no need
for base64!

[swiftyone]

As the file reader is not used any more it should also fix issues #37 and #31

[ihadeed]

According to the File plugin documentation, the tempDirectory is meant for temporary files that might not persist across app restarts. I haven't played around with the tempDirectory enough to figure out how it works. Did you experiment with it to see if the cache persists over a few sessions at least?

What if we add an option to customize the iOS behavior, to make sure everybody is happy. Available options can be:

• base64: returns a base64 image
• tempDir: implements your solution
• disable disable the caching completely and return the original URL

Not sure how the new Ionic WKWebView fork updates work, but I think they serve files via http:// protocol instead of file:///.

And I think the Base64 option will be helpful to develop with ionic run <platform> --livereload, so it might be a good idea to keep the functionality around.

[swiftyone]

In my experience the tempDirectory is usually persistent, I guess it is only removed if the device runs out of available space.
But I agree, it could be a good idea to keep the base64 option, even though I cannot recommend using it on a device, at least not in production.

I will implement the option next week!
Cheers!

[ihadeed]

Thanks @swiftyone

[swiftyone]

Alright, have a look at it!
Now all the files are copied to the temporary directory, if needed. This way there should be no problems with the persistence of the directory…
The usage of the temporary directory is automatically chosen if the device uses the WKWebView and the option is set to 'uri', if the user does not want that approach 'base64' needs to be used – otherwise it will not work anyhow.

Also I did use readAsDataURL for the base64 option to avoid directly using the FileReader, which can lead to some problems (#31).

I did not(!) include the 'disable' option, as I was not completely sure, if this is really necessary; I don't really see the benefit of it.

[ihadeed]

Looks good, thanks @swiftyone !