PKDrawing different results for Dark Mode and Light Mode

问题

When using PKDrawing in dark mode the image generated by imageFromRect:scale: returns pen drawings in white color. In light mode it uses black color. The background is usually transparent.

Question: How can PKDrawing be forced to always behave like in light mode?

回答1:

You can do it like this, by using traitCollection.performAsCurrent:

let darkImage = thumbnail(drawing: drawing, thumbnailRect: frameForImage, traitCollection: UITraitCollection(userInterfaceStyle: .dark))

func thumbnail(drawing: PKDrawing, thumbnailRect: CGRect, traitCollection: UITraitCollection) -> UIImage {

    var image = UIImage()
    traitCollection.performAsCurrent {
        image = drawing.image(from: thumbnailRect, scale: 2.0)
    }
    return image
}

来源：https://stackoverflow.com/questions/58303655/pkdrawing-different-results-for-dark-mode-and-light-mode