可以从图形数据初始化新的PKDrawing对象，并从中生成NSImage：

import PencilKit

do {
    let pkDrawing = try PKDrawing(data: drawingData)
    let nsImage = pkDrawing.image(from: pkDrawing.bounds, scale: view.window?.backingScaleFactor ?? 1)
} catch {
    print(error)
}