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
Fixes:
- Usage of UIScreen in -[ASDisplayNode init]
(the offending individual will be prosecuted)
- #38: Proper teardown of nodes owned by ASTableView / ASRangeController
- #34: Fix infinite recursion in very rare subclassing scenario
- #30: Avoid animating cell and section additions to ASTableView
- #19: Set a more reasonable default for maximum display concurrency
r=nadi
The documentation for `UITableViewDataSource` specifies that the default value is 1, and that its implementation is optional. However, ASTableView's forwarding doesn't account for the unimplemented case. The desired behavior is to return 1 in the case that the method is not implemented.
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`.
