Ndtyjky

I am currently experimenting with NightNight, an easy-to-use library to add light and dark themes to an app. I recommend looking into it if you are interested in adding two themes to your app.

That being said, it works like a charm. It is not fully supported yet, e.g. I am missing the ability to set the shadowImage of a UITabBarController to change the "top border" or separator, but I guess I can add this later by diving into the source.

One problem I am facing now, is that I am unable to change the color of attributedText of a UITextView. I definitely need to use the attributedText property because I want to add lineHeightMultiple. I got everything to work, but the color does not change when I switch between themes.

The UITextView is part of a UICollectionViewCell, so it is reused. Whenever I restart the app or start scrolling in the UICollectionView, the text is updated (sometimes - because of the reuse, it sometimes does not update when the cell remains visible on screen). It feels to me like I need to update or reload something else in order to get this library to work as I need.

Currently I set up my TextView like this:

let customTextViewStyle = NSMutableParagraphStyle()

customTextViewStyle.lineHeightMultiple = 1.2



let attributedString = NSMutableAttributedString(string: "This is the text that will be shown inside the TextView")



attributedString.setMixedAttributes([NNForegroundColorAttributeName: MixedColor(normal: lightCustomTextViewFontColor, night: darkCustomTextViewFontColor)], range: NSRange(location: 0, length: attributedString.length))

attributedString.addAttribute(NSAttributedString.Key.paragraphStyle, value: customTextViewStyle, range: NSRange(location: 0, length: attributedString.length))

attributedString.addAttribute(NSAttributedString.Key.font, value: UIFont.systemFont(ofSize: normalFontSize), range: NSRange(location: 0, length: attributedString.length))



customTextView.attributedText = attributedString

Below is a fragment of the source file from NightNight, which is called NSMutableAttributedString, where an observer is added:

public extension NSMutableAttributedString {

    fileprivate struct AssociatedKeys {

        static var mixedAttrsKey = "mixedAttrs"

    }



    fileprivate var mixedAttrs: [String: [NSRange: MixedColor]] {

        get {

            if let dict = objc_getAssociatedObject(self, &AssociatedKeys.mixedAttrsKey) as? [String : [NSRange : MixedColor]] {

                return dict

            }

            self.mixedAttrs = [:]



            MixedColorAttributeNames.forEach { (mixed) in

                self.mixedAttrs[mixed] = [:]

            }



            return self.mixedAttrs

        }

        set {

            objc_setAssociatedObject(self, &AssociatedKeys.mixedAttrsKey, newValue as AnyObject, .OBJC_ASSOCIATION_RETAIN_NONATOMIC)



            addNightObserver(#selector(_updateTitleAttributes))

        }

    }

}

Then _updateTitleAttributes looks like this:

@objc func _updateTitleAttributes() {



    MixedColorAttributeNamesDictionary.forEach { (mixed, normal) in

        if let foregroundColorDictionary = mixedAttrs[mixed] {

            foregroundColorDictionary.forEach({ (range, mixedColor) in

                self.addAttribute(normal, value: mixedColor.unfold(), range: range)

            })

        }



    }

}

I would highly appreciate a solution to this issue, as I myself am unable to figure it out. Does it have something to do with the source - e.g. does it not update properly? Does it have something to do with my UICollectionViewCell?

Thanks in advance!