Open Radar

 
At the moment, the most efficient way to retrieve a UIView snapshot as an image via public API is to set up a Core Graphics bitmap context (directly or via UIGraphicsImageRenderer) and call drawViewHierarchyInRect:afterScreenUpdates: method. However, it looks like the internal implementation detail of this method actually retrieves such snapshot image and draws it to the current context. This may be inefficient in certain use cases: it requires additional memory allocation, rendering and potentially color conversion, which may not be necessary at all if the intended usage of the image is just saving it to a file on disk, or retaining it and rendering later. So it would be great if there was a public API method that skips the redrawing part, and just returns a UIImage.
Of course, the image returned by the similar -[UIView _imageFromRect:] SPI can be CGImage-based (on Simulator) or IOSurface-based (on device), but _drawViewHierarchyInRect: (which uses it) seems to handle this conversion, so it's reasonable to expect the proposed public method to do the same.
drawViewHierarchyInRect:afterScreenUpdates: deals with screen updates on demand, but even if the proposed method doesn't support screen updates (and returns nil if the view is not rendered yet), that seems like an acceptable compromise.