This avoids CoreAnimation from capturing the name from a background thread deep within the internals
of AVPlayerLayer, which commits transactions off the main thread. If the main thread is also accessing
properties that require the lock, in very specific app architectures relying on AVPlayerLayer, this
can cause a deadlock.
The "name" property is primarily used by ASDK's unit test infrastructure, so I'm leaving it in place for
that purpose - and it may still be used for debugging, if someone wants to set it. It will remain
possible to get the node from a layer or view with asyncdisplaykit_node, and access name from there.
These have been superseded by -[ASDisplayNode initWithViewBlock:] and
-[ASDisplayNode initWithLayerBlock:], respectively -- the new API allows
for custom initialisers, but does not support asynchronous display.
The old initialisers are still available in ASDisplayNodeInternal.h, for
internal subclasses and daring adventurers.
This adds new initializer methods to ASDisplayNode:
```objc
initWithViewBlock:(ASDisplayNodeViewBlock)viewBlock
initWithLayerBlock:(ASDisplayNodeLayerBlock)layerBlock
```
Sometimes a view can't be constructed with `-[initWithViewClass:]` but you want to use it with ASDK, so these new methods provide a way to wrap an existing view in a node.
The API is meant to preserve ASDisplayNode's behavior, so you can still construct and set properties on the node on a background queue before its view is loaded; even though the view was created a priori, it is not considered to be loaded until `node.view` is accessed.
Using the API looks like this:
dispatch_async(backgroundQueue, ^{
ASDisplayNode *node = [ASDisplayNode alloc] initWithViewBlock:^{
// Guaranteed to run on the main queue
UIButton *button = [UIButton buttonWithType:UIButtonTypeSystem];
[button sizeToFit];
node.frame = button.frame;
return button;
}];
// Use `node` as you normally would...
node.backgroundColor = [UIColor redColor];
});
The main thing this bridging API doesn't do (can't do?) is layout. Methods like `-[ASDisplayNode calculateSizeThatFits:]` and `-[ASDisplayNode layout]` cannot delegate to `[UIView sizeThatFits:]` and `[UIView layoutSubviews]` since the UIView methods must run on the main thread. If ASDK were internally asynchronous and could dispatch its layout methods to different threads (sort of like how ASTableView computes its cells' layouts) then we could mark nodes with externally provided views/layers as having "main-queue affinity" and delegate its layout to UIKit.
Test cases are included and all existing tests pass.
Rename the ASDisplayNode property to match its _ASDisplayLayer
counterpart -- `displaySuspended` is more succinct and is a more
plausible name for a Cocoa BOOL property.
`-[ASDisplayNode addSubnodeAsynchronously::]` and
`-replaceSubnodeAsynchronously:::` are unused and confusingly increase
AsyncDisplayKit's API surface. `-addSubnode:` and friends are
thread-safe and can be used on background threads, so removing these
methods does not constitute a decrease in functionality.
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`.
Summary:
* Fixes#3
* Ordering: atomicity, then [optional] readonly, then value semantics (retain/copy/assign)
* Removed redundant `readwrite`
* No spaces between "getter = name" ("getter=name" instead)
* Property method overrides renamed as well
* self.isBlah, while technically not entirely correct, still resolves to [self blah], so left alone (@kimon had advice on this sort of naming issue last summer), and largely inconsequential
Test Plan:
* Compile and run
