This diff resolves all known consistency issues with ASTableView and ASCollectionView.
It includes significantly more aggressive thrash-testing in ASTableViewStressTest,
which now passes on a variety of device and simulator configurations. It also updates
the unit tests run on every commit to ensure any regression is caught quickly.
A few of the salient changes in this diff:
- ASTableView now uses Rene's ASCollectionViewLayoutController, and actually uses a
UICollectionViewFlowLayout without any UICollectionView. This resolves an issue where
ASFlowLayoutController was generating slightly out-of-bounds indicies when programmatically
scrolling past the end of the table content. Because the custom implementation is likely
faster, I will revisit this later with profiling and possibly returning to the custom impl.
- There is now a second copy of the _nodes array maintained by ASDataController. It shares
the same node instances, but this does add some overhead to manipulating the arrays. I've
filed a task to follow up with optimization, as there are several great opportunities to
make it faster. However, I don't believe the overhead is a significant issue, and it does
guarantee correctness in even the toughest app usage scenarios.
- ASDataController no longer supports calling its delegate /before/ edit operations. No
other class was relying on this behavior, and it would be unusual for an app developer to
use ASDataController directly. However, it is possible that someone with a custom view
that integrates with ASDataController and ASRangeController could be affected by this.
- Further cleanup of organization, naming, additional comments, reduced code length
wherever possible. Overall, significantly more accessible to a new reader.
This applies primarily when beginUpdates / endUpdates is not used.
Due to user interaction-driven edits, like reloads or adding content
at the bottom, sometimes this is unavoidable in app design and thus
critical.
I have a diff in flight to make ASDataController / ASRangeController
robust against very aggressive thrash testing, which will be added
both to the unit test suite and this new example project.
Most UITableViewCell properties aren't useful in conjunction with
ASCellNode -- the system's UIView properties are unsupported for
performance reasons, and properties that configure them (e.g., content
indentation) don't affect custom node hierarchies. This patch adds
support to _ASTableViewCell for the properties that *are* useful.
r=scottg
(1) We can't size nodes without a delegate, and if our owning controller
has been deallocated, our delegate will be nil. Handle this more
gracefully.
(2) Our teardown code needs to be executed on the main thread, but it's
conceivable that we might hit refcount 0 on a background queue. Force
deallocation to occur on the main thread.
Closes#27.
Introduce `ASTableView`, a UITableView subclass that uses `ASCellNode`
instead of UITableViewCell. Add working range support via
`ASRangeController`, which observes the visible range, maintains a
working range, and handles most ASDK machinery. ASRangeController is
loosely-enough coupled that it should be easily adapted to
UICollectionView if that's desired in the future.
Notable considerations in the ASRangeController architecture:
* There's no sense rewriting UITableView -- the real win comes from
using nodes instead of UITableViewCells (easily parallelisable
computation, large number of cells vs. few table views, etc.). So,
use a UITableView with empty cells, using UITableViewCell's
contentView as a host for arbitrary node hierarchies.
* Instead of lazy-loading cells the instant they're needed by
UITableView, load them in advance. Preload a substantial number of
nodes in the direction of scroll, as well as a small buffer in the
other direction.
* Maintain compatibility with UITableView's API, with one primary change
-- consumer code yields configured ASCellNodes, not UITableViewCells.
* Don't use -tableView:heightForRowAtIndexPath:. Nodes already compute
their preferred sizes and cache results for use at layout-time, so
ASTableView uses their calculatedSizes directly.
* Corollary: ASTableView is only aware of nodes that have been sized.
This means that, if a cell appears onscreen, it has layout data and
can display a "realistic placeholder", e.g. by making its subnodes'
background colour grey.
Other improvements:
* Remove dead references and update headers (fixes#7, #20).
* Rename `-[ASDisplayNode sizeToFit:]` to `-measure:` and fix
`constrainedSizeForCalulatedSize` typo (fixes#15).
* Rename `-willAppear` and `-didDisappear` to `-willEnterHierarchy` and
`-didExitHierarchy`. Remove `-willDisappear` -- it was redundant, and
there was no counterpart `-didAppear`.
* Rename `viewLoaded` to `nodeLoaded`.
