Add "Native Catalog" with advanced integration examples on iOS

[radazzouz]

Details

This PR adds the Native Catalog sample project on iOS. The sample project was originally added on Android in #318.

Code that needs to be reviewed (Is not Autogenerated)

• App.js.
• shared.js.
• README.md.
• All Objective-C Code.

Acceptance Criteria

• When approved, right before merging, rebase with master and increment the package version in package.json, package-lock.json, samples/Catalog/package.json, and samples/NativeCatalog/package.json (see example commit: 1bf805f).
• Create a new release (and tag) with the new package version (see https://github.com/PSPDFKit/react-native/releases).

[radazzouz]

This looked bad on iOS. On Android it looks okay with -10.

[steviki]

I think it would actually look nicer with this (at least on iOS, since the view is auto sized and the text doesn't go outside the safe area. I haven't tested it on Android though.)

<SafeAreaView
  style={{
    flexDirection: 'row',
    alignItems: 'center',
  }}>

Do you think we could use that?

[radazzouz]

Thanks @steviki! In 1223bab I switched to SafeAreaView and it looks great on iOS.

@irgendeinich when you have a minute can you please test the first two examples on Android to see SafeAreaView works correctly? I am no longer able to run the NativeCatalog on Android.

[radazzouz]

Using SafeAreaView also works great on Android.

Manual Signing Example	Watermark Example

[irgendeinich]

JS changes look good, and Android Catalog is still working as expected.

[steviki]

This looks good to me! 👍

Just a few small nitpicks.

And sorry for the late review!

[steviki]

I think it would actually look nicer with this (at least on iOS, since the view is auto sized and the text doesn't go outside the safe area. I haven't tested it on Android though.)

<SafeAreaView
  style={{
    flexDirection: 'row',
    alignItems: 'center',
  }}>

Do you think we could use that?

[steviki]

We don't actually need to register the signer, since we use it directly to sign the form element, instead of using the signature view.