requiresMainThread
A Boolean value that determines whether the system executes the print formatter’s rendering operations on the main thread.
Declaration
var requiresMainThread: Bool { get }Discussion
The default value is true, which requires the printing system to execute rendering operations, like drawing and page-count calculation, on the main thread. Override this property to return false if you want the system to execute operations like draw(in:forPageAt:) and pageCount on a background thread.