Cannot convert value of type 'NSAttributedString.DocumentAttributeKey' to expected dictionary key type 'NSAttributedString.DocumentReadingOptionKey' [duplicate]

Question

I have just updated to Xcode 9 and converted my app from swift 3 to swift 4 and get this errors. how i can fix this?

 func displayText() {
    do {
        if url.pathExtension.lowercased() != "rtf" {
            let fileContent = try String(contentsOf: url)
            text.text = fileContent
        } else { // Is RTF file
            let attributedString = try NSAttributedString(url: url, options: [NSDocumentTypeDocumentAttribute:NSRTFTextDocumentType], documentAttributes: nil)
            text.attributedText = attributedString
            text.isEditable = false
        }
    }

And get this Error

Cannot convert value of type 'NSAttributedString.DocumentAttributeKey' to expected dictionary key type 'NSAttributedString.DocumentReadingOptionKey'

Answer 1

In swift 4 - NSAttributedString representation is completely changed.

Replace your attribute dictionary key and value [NSDocumentTypeDocumentAttribute:NSRTFTextDocumentType]with [NSAttributedString.DocumentReadingOptionKey.documentType : NSAttributedString.DocumentType.rtf]

Try this:

func displayText() {
    do {
        if url.pathExtension.lowercased() != "rtf" {
            let fileContent = try String(contentsOf: url)
            text.text = fileContent
        } else { // Is RTF file
            let attributedString = try NSAttributedString(url: url, options: [NSAttributedString.DocumentReadingOptionKey.documentType : NSAttributedString.DocumentType.rtf], documentAttributes: nil)
            text.attributedText = attributedString
            text.isEditable = false
        }
    }
}

Here is note from Apple: NSAttributedString - Creating an NSAttributedString Object