雨燕3

if let rtfPath = Bundle.main.url(forResource: "SomeTextFile", withExtension: "rtf") {
            do {
                let attributedStringWithRtf:NSAttributedString = try NSAttributedString(url: rtfPath, options: [NSDocumentTypeDocumentAttribute:NSRTFTextDocumentType], documentAttributes: nil)
                self.textView.attributedText = attributedStringWithRtf
            } catch let error {
                print("Got an error \(error)") 
            }
        }

雨燕4和5

if let rtfPath = Bundle.main.url(forResource: "someRTFFile", withExtension: "rtf") {
        do {
            let attributedStringWithRtf: NSAttributedString = try NSAttributedString(url: rtfPath, options: [NSAttributedString.DocumentReadingOptionKey.documentType: NSAttributedString.DocumentType.rtf], documentAttributes: nil)
            self.textView.attributedText = attributedStringWithRtf
        } catch let error {
            print("Got an error \(error)")
        }
    }

if let rtfPath = NSBundle.mainBundle().URLForResource("description_ar", withExtension: "rtf") 
{
    let attributedStringWithRtf = NSAttributedString(fileURL: rtfPath, options: [NSDocumentTypeDocumentAttribute:NSRTFTextDocumentType], documentAttributes: nil, error: nil)
    self.textView.attributedText = attributedStringWithRtf
}

您可以在Swift 2中使用以下代码读取rtf文件。

加载RTF文件

let path = NSBundle.mainBundle().pathForResource("sample-rtf", ofType: "rtf")

    let contents: NSString
    do {
        contents = try NSString(contentsOfFile: path!, encoding: NSUTF8StringEncoding)
    } catch _ {
        contents = ""
    }

    let array : NSArray = contents.componentsSeparatedByString("\n");

    self.textView.text  = (array.objectAtIndex(0) as! String);

    //self.textView.text  = contents as String

尝试使用纯文本（txt）文件而不是rtf文件。RTF文件也包含文本的格式信息。这是你在阅读内容后看到的不必要的东西。
在Mac文本编辑中打开rtf文件，然后按Cmd+Shift+T（这会将其转换为纯文本并删除所有格式），然后保存为txt。

加载文本文件

let path = NSBundle.mainBundle().pathForResource("sample-text", ofType: "txt")

    let contents: NSString
    do {
        contents = try NSString(contentsOfFile: path!, encoding: NSUTF8StringEncoding)
    } catch _ {
        contents = ""
    }

     self.textView.text  = contents as String

Swift 3代码：

if let rtfPath = Bundle.main.url(forResource: "description_ar", withExtension: "rtf") {
    do {
        let attributedStringWithRtf:NSAttributedString = try NSAttributedString(url: rtfPath, options: [NSDocumentTypeDocumentAttribute:NSRTFTextDocumentType], documentAttributes: nil)
            self.textView.attributedText = attributedStringWithRtf
        } catch {
            print("We got an error \(error)") //or handle how you want
        }
}

受@MikeG启发的编辑和更新
10月21日更新，灵感来自@RAJAMOHAN-S和@生物标记