ASDisplayNodes now have an overidable method -placeholderImage that lets you provide a custom UIImage to display while a node is displaying asyncronously. The default implementation of this method returns nil and thus does nothing. A provided example project also demonstrates using the placeholder API.
Use ASBasicImageDownloader by default -- you can now do...
ASNetworkImageNode *imageNode = [[ASNetworkImageNode alloc] init];
imageNode.URL = [NSURL URLWithString:@"..."];
[self.view addSubview:imageNode.view];
...and it'll do the right thing.
Working-range-driven image loading.
(Note that ASNetworkImageNode and ASMultiplexImageNode haven't yet been
updated to work with the new `-reclaimMemory`-based working range
system, so this doesn't quite behave correctly yet.)
ASDisplayNode and several subclasses had previously cleared memory-heavy
objects like the backing store and text layout manager when the node's
view
or layer is removed from a visible heirarchy. This works great in any
system
that uses a "working range", where exiting the range removes the node
from
the hierarchy and reclaiming memory at that time is important.
However, for
standard UIViewController patterns (unused in Paper), this behavior
causes
highly undesirable thrashing (leading to visible flashes & wasteful
re-rendering of content).
After this change, node subclasses should implement -reclaimMemory if
they
need to perform any other cleanup besides backing store destruction
when they
leave a working range or other scenario where memory reduction is
valuable.
To trigger this behavior, calling code should use
-recursivelyReclaimMemory.
r=nadi
