CGContextSaveGState: invalid context 0x0 (Xcode 7 GM)
I'm drawing using UIBezierPath
Removing path.fill()
removed the warning.
This also happens for me on 7 GM, but removing UIViewControllerBasedStatusBarAppearance
from Info.plist fixed it for me, as said here.
Update: Warning seems to be gone with iOS 9.2