* Fix some concurrency problems detected by Xcode 8's new Thread Sanitizer.
Some of these changes are arguably just to silence the warnings from Thread Sanitizer.
* Fix several memory leaks in the unit tests.
A number of the unit test source files are compield with `-fno-objc-arc`. This was clearly overlooked when writing several of the unit tests.
Fixed by (mostly) switching to use of `-autorelease` for the problem code.
NOTE: This commit doesn't fix all the memory leaks found. There's still at least one leak in `-[ASDisplayNodeTests testSetNeedsDataFetchImmediateState]`, and several leaks in `ASBasicImageDownloader.mm`. I wasn't able to find a trivial cause to these, unfortunately.
* [Travis CI] Build Optimizations
* update cocoapods versionm
* test sharing derived data directories
* Hack to reduce travis run time
* Remove test file
* Add missing slashes
- Add locking to _linkAttributeValueAtPoint:attributeName:range:inAdditionalTruncationMessage:forHighlighting: as we access the attributed text in there
- Add locking to touchesBegan:withEvent: as we are accessing the [ASTextKitRenderer firstVisibleRange]
- Add locking for highlightStyle
- Move accessing delegate property access to instance variable access
I looked into the internals of UIImageView a bit. I would recommend to not fixing this in a universal way. UIImageView is specifically optimized for performance and does not use the usual way to provide the contents of the CALayer that backs the UIImageView.
Furthermore we cannot trigger a recreation of the contents of the UIImageView layer as if it get’s cleared and we call setNeedsDisplay on it it goes trough the normal flow to assign the contents to a layer via the CALayerDelegate methods. Unfortunately UIImageView does not do it, it actually does not implement some of the methods at all, so nothing will show up. It’s getting better, by calling setNeedsDisplay on an UIImageView layer it actually clears the contents and nothing is visible anymore. So we have to be careful to not calling that too.
Unfortunately I didn’t find a way yet to trigger a recreation of the UIImageView layers content except calling the private _updateState method.
That said it’s different for layers of other UIKit components like UILabel for example. Clearing the contents of a UILabel layer and calling setNeedsDisplay on the layer usually recreates the contents of the it and it will show up again.
This commit prevents to clear the contents of a layer for all wrapped UIKit and instead only NOT clear the content if the node wraps a UIImageView otherwise we should clear the contents of the layer to reclaim memory as usual.
Rounding up to the next device pixel was calculating a height smaller
than UITextView's contentSize. This was causing the baseline to move as
the user was typing.
