Search functionality

[tevelee]

Introduction

The following changes introduce a basic search functionality in the tweaks UI as proposed in issue #115. Tweaks are searchable using a single search query on the category- and the collection lists as well.

Features

• Tweaks can be filtered using a simple text query
• Search is available on the top of the categories and collections lists as well
• Searching filters the list of tweaks using case- and diactric insensitive match
• The filtered list keeps the tweak hierarchy using sections
• The search gets highlighted in the matching rows

Technical considerations for the reviewer

• The list of changes are compatible with the supported minimum (iOS 6) APIs
• In order to reduce code duplication and improve maintainability I introduced a helper class which is accessible from both view controllers. Its two methods handle model filtering and tweak selection as those are needed in both ViewControllers.
• Since tweaks nor categories or collections support NSCopying, during the filtering I needed to create new collections (which are not part of the tweak store), and build a new list of these collections for the filtered list. This makes some FBTweaks be part of two collections at once.

Enhancements to consider

• Fuzzy search
• Introducing multiple search scopes (Searching on the categories list can filter only the visible list itself - as category scope - or filter the whole tweak repository - as a full scope - as it is currently implemented)
• Search bar could be hidden by default so a pull-down gesture could reveal it
• Reduce code duplication even more by moving cell creation into the helper utility class

[tevelee]

Hi @grp @sgl0v @johntmcintosh @callumboddy,

Can somebody please review this feature?
Many thanks!

[tevelee]

I believe this PR is still valid. Can somebody take a look, please?