Creates a bitmap-based graphics context and makes it the current context.
- iOS 2.0+
- tvOS 9.0+
- watchOS 2.0+
The size of the new bitmap context. This represents the size of the image returned by the
Get Image From Current Image Context()
This function is equivalent to calling the
UIGraphics function with the opaque parameter set to
false and a scale factor of
This function may be called from any thread of your app.