iosswiftalignmentnsattributedstringnstexttab

How to remove TapStops location recursively using enumerateAttributes in iOS

I've to show HTML data in UITextView, this HTML data sometimes contains nested tags for lists, which cause extra padding on device, I want to remove extra padding using swift side since padding from CSS doesn't seem to be working here. Here is how my code and sample data looks like

let mutableAttributedString = NSMutableAttributedString(attributedString: attributedQuestionMessage!)
    mutableAttributedString.enumerateAttributes(in: NSMakeRange(0, mutableAttributedString.length), options: []) { (attributes, range, stop) in
        let maybeParagraphStyles = attributes.filter {$0.key == NSAttributedStringKey.paragraphStyle }
        maybeParagraphStyles.forEach({ (style) in
            if let paragraphStyle = style.value as? NSParagraphStyle {
                let mutableParagraphStyle = paragraphStyle.mutableCopy() as! NSMutableParagraphStyle

                let modifiedTabStops = mutableParagraphStyle.tabStops.map {
                    NSTextTab(textAlignment: $0.alignment, location: $0.location - mutableParagraphStyle.defaultTabInterval, options: $0.options)
                }
                if modifiedTabStops.count > 0 {
                    mutableParagraphStyle.tabStops = modifiedTabStops
                }
                var mutableAttributes = attributes

                mutableAttributes[NSAttributedStringKey.paragraphStyle] = mutableParagraphStyle
                mutableAttributedString.removeAttribute(.paragraphStyle, range: range)
                mutableAttributedString.addAttribute(.paragraphStyle, value: mutableParagraphStyle, range: range)
            }
        })

    }
    textView.attributedText = mutableAttributedString

this works fine, but fails for when I've to display data like this 

<html> <head> <style type="text/css"> 
 body {  font-size: 14px;  font-family: -apple-system,
 Arial, sans-serif; color: black; margin-bottom: 0px;
 padding-bottom: 0px; line-height: 20px; } </style> </head> 
<body> <p>To make this more tangible, let’s bring this concept to 
the team level. What would you say are the aspirations for your 
team?</p>
<ul><ul type="disc"><li>What is the overall goal?
<ul><ul style="list-style-type:circle"><li>E.g., Increase customer 
loyalty by 20% as measured by Repeat Customer Rate</li></ul></ul></li>
<li>What specific initiatives do you think would lead you to achieve 
it?<ul><ul style="list-style-type:circle"><li>E.g., Implement a loyalty
program that rewards customers each time they purchase a certain value
 of items</li></ul></ul></li></ul></ul> </body> </html>

which show data like this, as you can see there is alignment issue & padding too, any suggestions ? enter image description here

Solution

  • As you can see it's obvious in the code that I'm reducing NSTextTab by subtracting it defaultTabInterval from it, head indent of paragraphStyle is equivalent to in this case modifiedTabStops.last?.location, since I was changing the location of both tabs of NSTextTab, changing the headIndent solve my problem. Here is the solution.

        let mutableAttributedString = NSMutableAttributedString(attributedString: attributedQuestionMessage!)
    mutableAttributedString.enumerateAttributes(in: NSMakeRange(0, mutableAttributedString.length), options: []) { (attributes, range, stop) in
        let maybeParagraphStyles = attributes.filter {$0.key == NSAttributedStringKey.paragraphStyle }
        maybeParagraphStyles.forEach({ (style) in
            if let paragraphStyle = style.value as? NSParagraphStyle {
                let mutableParagraphStyle = paragraphStyle.mutableCopy() as! NSMutableParagraphStyle

                let modifiedTabStops = mutableParagraphStyle.tabStops.map {
                    NSTextTab(textAlignment: $0.alignment, location: $0.location - mutableParagraphStyle.defaultTabInterval, options: $0.options)
                }

                if modifiedTabStops.count > 0 &&  mutableParagraphStyle.headIndent > mutableParagraphStyle.defaultTabInterval {
                    if let location = modifiedTabStops.last?.location {
                        mutableParagraphStyle.headIndent = location
                    }
                    mutableParagraphStyle.tabStops = modifiedTabStops
                }
                var mutableAttributes = attributes
                mutableAttributes[NSAttributedStringKey.paragraphStyle] = mutableParagraphStyle
                mutableAttributedString.removeAttribute(.paragraphStyle, range: range)
                mutableAttributedString.addAttribute(.paragraphStyle, value: mutableParagraphStyle, range: range)
            }
        })

    }