xcode output some log when tap btnCamera

[scaupdc]

I am using xcode 6.3 and I have check out the latest UzysAssetsPickerController.
xcode's output window print the follow info when I tap btnCamera:
Snapshotting a view that has not been rendered results in an empty snapshot. Ensure your view has been rendered at least once before snapshotting or snapshot after screen updates.
I don't know whether it is a bug?Because UzysAssetsPickerController works well so far.