Images and Darkmode not switching

Question

In a couple of my apps, I have an image covering the view in the background. In my asset catalog, my image has an Any, light and dark variation. In iOS 13, when I launch the app, the correct light or dark mode image is displayed according to the mode set. However, when I switch the mode while the app is running, the image does not change. All other properties change (colors etc) for all controls, but not the image. I have tried the following with a layoutIfNeeded() and/or layoutSubviews() inside the traitCollectiosnDidChange block:

 override func traitCollectionDidChange(_ previousTraitCollection: UITraitCollection?) {
    super.traitCollectionDidChange(previousTraitCollection)
    guard let previousTraitCollection = previousTraitCollection else {return}
        if #available(iOS 13.0, *) {
            if previousTraitCollection.hasDifferentColorAppearance(comparedTo: traitCollection) {
            print("Changed mode")
            self.view.layoutIfNeeded()
            self.view.layoutSubviews()
        }
    }
}

and the Change mode is definitely triggered but the layout does not change. Is there a way to make sure that the image also displays the correct one?

Interesting. How do you set the image? Is it working if you re-set the image in `traitCollectionDidChange`? — Frank Rupprecht, Sep 16 '19 at 18:51

score 4 · Answer 1 · edited Sep 18 '19 at 10:33

OK. To answer my own question. I was applying .withHorizontallyFlippedOrientation() to my image and setting it in ViewDidLoad. When I changed the trait color mode, this image was not getting change. The solution was to to reset the image AND the flip property when the differentColorAppearance triggers. Like this

override func traitCollectionDidChange(_ previousTraitCollection: UITraitCollection?) {
    super.traitCollectionDidChange(previousTraitCollection)
    guard let previousTraitCollection = previousTraitCollection else {return}
    if #available(iOS 13.0, *) {
        if previousTraitCollection.hasDifferentColorAppearance(comparedTo: traitCollection) {
            image2.image = UIImage(named: "CourseImage")?.withHorizontallyFlippedOrientation()
    }
  }
}

Images and Darkmode not switching

1 Answers1