Swift- How to remove attributed string values and make it appear as normal string. (Bold, Italic, Un-CodePudding

I want to remove attributed string values and make it appear as normal string. (Bold, Italic, Underline, Strikethrough)

I have added below code to make it attributed but I want to know how do i remove these attributes from the string when clicked on that action again.

Bold - 

   if textBold == true {
                            let string = text
                            let attributes: [NSAttributedString.Key: Any] = [
                                .font: UIFont.boldSystemFont(ofSize: 25)
                            ]
                            let attributedString = NSAttributedString(string: string, attributes: attributes)
                            modifiedString = attributedString
                            text_View.attributedText = modifiedString

                            text_View.sizeToFit()
                            databaseHandlerObj.editLabelData(textProjectId: fetchTextProjectId, text_Id: fetchTextId, text: modifiedString.string)
                        }

Italic - 
        if textItalic == true {

                            text_View.sizeToFit()
                            let string = text
                            
                            let attributes: [NSAttributedString.Key: Any] = [
                                .font: UIFont.italicSystemFont(ofSize: CGFloat(fontSize))
                            ]
                            let attributedString = NSAttributedString(string: string, attributes: attributes)
                            self.modifiedString = attributedString
                            text_View.attributedText = modifiedString
                            
                            databaseHandlerObj.editLabelData(textProjectId: fetchTextProjectId, text_Id: fetchTextId, text: modifiedString.string)
                        }

Underline -
   if textUnderline == true {
                            text_View.sizeToFit()
                            let string = text
                            let attributedString = NSMutableAttributedString.init(string: string)
                            attributedString.addAttribute(NSAttributedString.Key.underlineStyle, value: 1, range:
                                                            NSRange.init(location: 0, length: attributedString.length))
                            self.modifiedString = attributedString
                            text_View.attributedText = modifiedString
                            
                            databaseHandlerObj.editLabelData(textProjectId: fetchTextProjectId, text_Id: fetchTextId, text: modifiedString.string)
                        }
                        

Strikethrough - 
      if textStrikethrough == true {
                            text_View.sizeToFit()
                            let string = text
                            let attributeString: NSMutableAttributedString =  NSMutableAttributedString(string: string)
                            attributeString.addAttribute(NSAttributedString.Key.strikethroughStyle, value: 2, range: NSMakeRange(0, attributeString.length))
                            self.modifiedString = attributeString
                            text_View.attributedText = modifiedString
                            databaseHandlerObj.editLabelData(textProjectId: fetchTextProjectId, text_Id: fetchTextId, text: modifiedString.string)
                        }

CodePudding user response：

You need to use a NSMutableAttributedString. On it you can use the removeAttribute(_ name: NSAttributedString.Key, range: NSRange) method where you specify the range e.g. the whole string where you want to remove the attribute.

Apple documentation

CodePudding user response：

You need to enumerate the attributes on the NSAttributedString, and change or remove them.

With a little help from another question to know if a font is bold/italic

extension UIFont {
    var isBold: Bool {
        return fontDescriptor.symbolicTraits.contains(.traitBold)
    }

    var isItalic: Bool {
        return fontDescriptor.symbolicTraits.contains(.traitItalic)
    }
}

To simplify "your true logic":

extension NSAttributedString {

    enum Effects {
        case bold
        case italic
        case underline
        case strikethrough
    }

    var fullRange: NSRange {
        NSRange(location: 0, length: length)
    }
}

This should do the trick:

func remove(effects: NSAttributedString.Effects, on attributedString: NSAttributedString, range: NSRange) -> NSAttributedString {

    let mutableAttributedString = NSMutableAttributedString(attributedString: attributedString)

    mutableAttributedString.enumerateAttributes(in: range, options: []) { attributes, subrange, pointee in
        switch effects {
        case .bold:
            if let currentFont = attributes[.font] as? UIFont, currentFont.isBold {
                let newFont = UIFont.systemFont(ofSize: currentFont.pointSize)
                // Since we can only have one attribute at a range (and all subranges including in it)
                // there is no need to remove then add, adding it will replace the previous one
                mutableAttributedString.addAttribute(.font, value: newFont, range: subrange)
            }
        case .italic:
            if let currentFont = attributes[.font] as? UIFont, currentFont.isItalic {
                let newFont = UIFont.systemFont(ofSize: currentFont.pointSize)
                // Since we can only have one attribute at a range (and all subranges including in it)
                // there is no need to remove then add, adding it will replace the previous one
                mutableAttributedString.addAttribute(.font, value: newFont, range: subrange)
            }
        case .strikethrough:
            if attributes[.strikethroughStyle] != nil {
                mutableAttributedString.removeAttribute(.strikethroughStyle, range: subrange)
            }
            if attributes[.strikethroughColor] != nil { 
                mutableAttributedString.removeAttribute(.strikethroughColor, range: subrange)
            }
        case .underline:
            if attributes[.underlineColor] != nil {
                mutableAttributedString.removeAttribute(.underlineColor, range: subrange)
            }
            if attributes[.underlineStyle] != nil {
                mutableAttributedString.removeAttribute(.underlineStyle, range: subrange)
            }
        }
    }
    return mutableAttributedString
}

In Playground, you can test with:

let boldText = NSAttributedString(string: "Bold text", attributes: [.font: UIFont.boldSystemFont(ofSize: 25)])
let unboldText = remove(effects: .bold, on: boldText, range: boldText.fullRange)
let italicText = NSAttributedString(string: "Italic text", attributes: [.font: UIFont.italicSystemFont(ofSize: 25)])
let unItalicText = remove(effects: .italic, on: italicText, range: italicText.fullRange)
let underlineText = NSAttributedString(string: "Underline text", attributes: [.underlineStyle: 1])
let unUnderlineText = remove(effects: .underline, on: underlineText, range: underlineText.fullRange)
let strikethroughText = NSAttributedString(string: "Strikethrough text", attributes: [.strikethroughStyle: 2])
let unStrikethroughText = remove(effects: .strikethrough, on: strikethroughText, range: strikethroughText.fullRange)

let attributedStrings = [boldText, unboldText, italicText, unItalicText, underlineText, unUnderlineText, strikethroughText, unStrikethroughText]

let fullAttributedString = attributedStrings.reduce(into: NSMutableAttributedString()) {
    $0.append(NSAttributedString(string: "\n"))
    $0.append($1)
}

The following test is to ensure that if there are other effects on the `NSAttributedString`, they aren't removed.

let textView = UITextView(frame: CGRect(x: 0, y: 0, width: 500, height: 200))
textView.backgroundColor = .yellow
textView.attributedText = fullAttributedString
textView
textView.attributedText = remove(effects: .bold, on: fullAttributedString, range: fullAttributedString.fullRange)
textView
textView.attributedText = remove(effects: .italic, on: fullAttributedString, range: fullAttributedString.fullRange)
textView
textView.attributedText = remove(effects: .underline, on: fullAttributedString, range: fullAttributedString.fullRange)
textView
textView.attributedText = remove(effects: .strikethrough, on: fullAttributedString, range: fullAttributedString.fullRange)
textView

Nota bene: You currently are doing bold OR italic, not both at the same time, since it's in this property is inside the UIFont, you'd need to find a bold AND italic font at the same time.
So if you want to remove an italic from a italic AND bold, you'd need to get the bold. I consider it as another scope, but there are questions about that.

Nota bene 2:

When you want to remove the attributes, I check for the presence of the attributes, but there is no need:

So:

if attributes[.someAttribute] != nil {
    mutableAttributedString.removeAttribute(.someAttribute, range: subrange)
}

Could just be:

mutableAttributedString.removeAttribute(.someAttribute, range: subrange)

Nota bene 3:

func remove(effects: NSAttributedString.Effects, on attributedString: NSAttributedString, range: NSRange) -> NSAttributedString

Could be an extension on NSAttributedString/NSMutableAttributedString instead.