[feature/disallow-extensions] Add option to disallow extensions, show action for unviewable filetypes

[felix-schwarz]

Description

This pull request adds to new features:

• the ability to disallow extensions via the new extensions.disallow MDM/branding option
• displays a fallback action (Open in) in case no suitable viewer is available for a filetype

Example

To block the QuickLook preview and webview viewer extensions, this would need to be added to the Branding.plist

<key>extensions.disallowed</key>
<array>
    <string>org.owncloud.ql_preview</string>
    <string>org.owncloud.webview</string>
</array>

Related Issue

https://github.com/owncloud/enterprise/issues/5308

Screenshots (if appropriate):

Previously	Now	Now when tapping the button

Types of changes

• [ ] Bug fix (non-breaking change which fixes an issue)
• [x] New feature (non-breaking change which adds functionality)
• [ ] Breaking change (fix or feature that would cause existing functionality to change)

Checklist:

• [ ] My code follows the code style of this project.
• [ ] My change requires a change to the documentation.
• [ ] Added an issue with details about all relevant changes in the iOS documentation repository.
• [ ] I have read the CONTRIBUTING document.
• [ ] I have added tests to cover my changes.
• [ ] All new and existing tests passed.
• [ ] Added changelog files for the fixed issues in folder changelog/unreleased

[CLAassistant]

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1 out of 2 committers have signed the CLA.

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:x: felix-schwarz
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[felix-schwarz]

Merged into #1162. No longer destined to be merged in 11.x outside of special builds.

[jesmrec]

QA checks:

• [x] extensions.disallowed
  • [x] quicklook -> tested with office files
  • [x] webview -> html, css, gif, json, x-php
• [x] excluded system activities
  • [ ] Add to reading list
  • [x] Copy to pasteboard
  • [x] Print
  • [x] Save to camera roll (displayed as Save Image)
  • [x] Mail
  • [x] Messages
  • [x] Assign to contact
  • [x] AirDrop
  • [x] Open in (i)Books
  • [x] Markup as PDF
• [x] Open in when preview is not available

[jesmrec]

Feature working fine, but two SystemActivities i was not able to work with:

• com.apple.UIKit.activity.AddToReadingList. As the Apple documentation states: When using this service, you can provide an [NSURL](https://developer.apple.com/documentation/foundation/nsurl) object whose contents uses the http or https scheme that points to the page to add.

Not clear which kind of file applies to that or how to reproduce correctly

• com.apple.UIKit.activity.OpenInIBooks: tested with an eBook file (.epub format). Open in shows the Apple's Books app with

<key>action.excludedSystemActivities</key> 
  <array>
    <string>com.apple.UIKit.activity.OpenInIBooks</string>
  </array>

Mechanism is pretty correct, just commented these two cases as non-reproducible.

[felix-schwarz]

The documentation on Apple's side may not be complete - or excluding Apple Books not being possible a system limitation. Thanks for documenting this.

I'm closing this PR as it has been merged into #1162.