Thread Safe (CG) Version of UIGraphicsGetImageFromCurrentImageContext?

Im trying to render PDF pages to imag开发者_如何学Pythones on a background thread, is there a thread safe way of generating an image from a pdfContext/context that doesn't not use:

UIGraphicsGetImageFromCurrentImageContext

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AFAIK (almost) all Core Graphics calls should be safe to use in a background thread as long you don't draw on screen and don't share resources (such as graphics contexts) among multiple threads.