- Only update range mode if visibility changes if the node is not range controlled
- Only change explicitly set range mode if ASRangeController becomes visible
- Return interface state for range controller in ASCollectionView and ASTableView based on if the containing node is range managed
- optimized ASRecursivelyFindIndexPathsForMultidimensionalArray() to remove enumerateUsingBlock:
- replaced single project call to ASIndexPathsForMultidimensionalArray() in ASRangeController with ASIndexPathsForTwoDimensionalArray()
Use this array while enumerating ASRangeController instances in response to UIApplication notifications,
as it is possible for these events to trigger the mutation of the ASWeakSet and cause an enumeration error.
Introduces ASLayoutRangeModeVisibleOnly, allowing the preservation of decoded backing stores without any extra padding to
strictly minimize memory usage while supporting immediate re-display of content. Set visible range controllers to this mode
upon app suspend / memory warning, while more aggressively clearing others to the ASLayoutRangeModeLowMemory mode.
By default, when the app is running and recieves a memory warning, we set the range mode for non-visible controllers to
ASLayoutRangeModeVisibleOnly. This is because, unlike in the app suspend case where on app resume we can restore controllers
from LowMemory to VisibleOnly, the memory warning doesn't provide a good opportunity to do this.
A new +Beta API to control this behavior is called +setRangeModeForMemoryWarnings:, as some apps may prefer to use LowMemory
in the memory warning scenario. For these apps, optimal user experience will require manually setting the range mode back
to some larger value as the user navigates the app, or they will encounter controllers that are temporarily blank and need
a moment to re-display their contents as they start to become visible.
These optimizations are surprisingly impactful. -setNeedsDisplay being called
for every node triggered cancelAsyncDisplay, locking, and memory management overhead
that is completely avoidable because Core Animation triggers first display automatically.
The mutable array copy optimizations reduced this key cost by over 10x, from 52ms to 5ms
on an iPad Air 2 / A8X with a real-world test case.
