* Add unit test to test trait collection changes occur during updates are handles correctly
* Remove handling code in ASDataController:updateWithChangeSet. Previous test should fail
* Correctly handle trait collection changes that occur mid-updates
- Currently, when there is a new trait collection, we correctly propagate it to all visible elements. However, since the propagating block is executed on main thread immediately without waiting for the background editing queue of ASDataController, not all elements are updated.
- Then to fix that, we updated ASDataController to handle these changes inside updateWithChangeSet. This works, but it doesn’t address the underlying issue.
- We now delegate the propagating task to ASDataController which schedule a block to its main serial queue after waiting for its background editing queue.
- It's not safe to hold the lock of a supernode and:
- Edit states of its subnodes
- Call subclass hooks
- Run completion block
- Run animation, which can trigger layout passes on subnodes, especially if one of them is a collection view.
* Avoid multiple initial data loads being issued by UICollectionView/UITableView
- Currently, there is a gap between the moment UICollectionView/UITableView triggers its first data load and when ASDataController finishes processing it. During this gap, the view keeps issuing "initial" loads by calling reloadData and causes its data controller to reload multiple times.
- Fix by immediately forward the first reloadData call to UICollectionView/UITableView before letting its data controller to handle it for real. During the gap, the view thinks that it loaded initial data but is empty, and thus stops triggering initial loads. Once the data controller finished loading, it will call another reloadData on the view which causes the view to swap to a correct state.
* Fix tests
* Use the existing flag of ASDataController
* Explain unit test
* [ASTextNode] Reset _composedTruncationText when attributedText is updated
Current issue:
1) Set `attributedText` in `ASTextNode` with whiteColor
2) `_composedTruncationText` gets updated to take on this new color attribute
3) Set the `attributedText` with greenColor
4) The `_composedTruncationText` gets updated with the new attributes, but does NOT overwrite any existing attributes — i.e., does not overwrite the white color with green. Comment from `_locked_prepareTruncationStringForDrawing:`:
`
// Add any of the original string's attributes to the truncation string,
// but don't overwrite any of the truncation string's attributes
`
* michael’s suggestion
* Fix trait collection handling in ASCollectionElement
- Don't store a trait environment directly and request it when needed. The environment is often the cotaining collection/table node. Asking it for a trait collection is an upward tree traversal and can cause deadlocks. This reverts #2963.
- If the environment changes during a change set update, notify all visible elements about the change. This fixes#2959.
* Address comments
