canDraw
A Boolean value indicating whether drawing commands will produce any results.
Declaration
var canDraw: Bool { get }Discussion
The value of this property is true when drawing produces expected results. A view object can draw onscreen if it is not hidden, it is attached to a view hierarchy in a window (NSWindow), and the window has a corresponding window device. A view object can also draw during printing if it is a descendant of the view being printed.
Check the value of this property before attempting to force drawing to a specific context. For example, if the value of this property is false, do not call lockFocus() or do issue any drawing commands from the view. You do not need to check whether drawing can occur when calling the display() method or any of its related methods. The display methods perform appropriate checks before asking the view to draw itself.