Summary:
I had a desire for interactive reordering in a personal project, so here's a first attempt at adding support in IGListKit.
I figured I might as well get a WIP PR up for comments before I continue further as there are a few aspects to interactive reordering that don't interplay perfectly with IGListKit.
As discussed in #291, I went after two prime use cases:
1. Moving items amongst a section
2. Rearranging whole sections
I also "disabled" moving items between sections by having those moves revert, to mimic interactive reordering cancellation as closely as possible.
You can see both in the Mixed Data example. Grid items can be moved within a section, while users can be moved to reorder whole sections. But trying to move a grid item out of a grid or a user item into a grid will auto-revert. The revert animation isn't as tight as it should be. It may be more desirable to disable the animation - though you lose the visual cue.
There is a also a new example, `ReorderableViewController`, that demonstrates 2 in its pure form (likely the most desired use case), where all sections are reorderable single rows.
Happy to take feedback -- this is my first experience working on IGListKit, so I would expect there to be gaps. (Ex. I haven't used `IGListStackedSectionController`, and its tests failed as I hadn't implemented reordering delegates for it. Those are simply stubbed out for now.)
Issue fixed: #291
- [x] All tests pass. Demo project builds and runs.
- [x] I added tests, an experiment, or detailed why my change isn't tested.
- [x] I added an entry to the `CHANGELOG.md` for any breaking changes, enhancements, or bug fixes.
- [x] I have reviewed the [contributing guide](https://github.com/Instagram/IGListKit/blob/master/.github/CONTRIBUTING.md)
- [x] Proper support in `IGListStackedSectionController`
Closes https://github.com/Instagram/IGListKit/pull/976
Differential Revision: D6674493
Pulled By: rnystrom
fbshipit-source-id: cd53c5fdc6fb59636edc4747c4bbd0f81a4610e5
