adddoccomment.swift

        for selection in invocation.buffer.selections {
            for lineIndex in selection.start.line...selection.end.line {
                guard let line = invocation.buffer.lines[lineIndex] as? String else { continue }
                guard !line.hasPrefix("/// ") else { continue }
                
                let newLine = "/// " + line
                
                invocation.buffer.lines[lineIndex] = newLine
                updatedSelections.append(
                    {
                        $0.start = XCSourceTextPosition(line: lineIndex, column: 0)
                        $0.end   = XCSourceTextPosition(line: lineIndex + 1, column: 0)
                        return $0
                    }(XCSourceTextRange()))
            }
        }
        if !updatedSelections.isEmpty {
            invocation.buffer.selections.setArray(updatedSelections)
        }
        completionHandler(nil)
    }

fetchselectionasstring.swift

    func getSelection(_ index: Int, _ invocation: XCSourceEditorCommandInvocation) -> String? {
        guard index < invocation.buffer.selections.count else { return nil }
        let selection = invocation.buffer.selections[index]
        let lines = invocation.buffer.lines
        var output = ""
        
        for lineIndex in selection.start.line...selection.end.line {
            var line = lines[lineIndex]
            if lineIndex == selection.end.line {
                line = line.substring(to: selection.end.column)
            }
            if lineIndex == selection.start.line {
                line = line.substring(to: selection.start.column)
            }
            print(line, terminator: "", to: &output)
        }
        return output
    }

removedoccoment.swift

    func perform(with invocation: XCSourceEditorCommandInvocation, completionHandler: (NSError?) -> Void ) -> Void {
        var updatedSelections: [XCSourceTextRange] = []
        
        for selection in invocation.buffer.selections {
            for lineIndex in selection.start.line...selection.end.line {
                
                guard let line = invocation.buffer.lines[lineIndex] as? String else { continue }
                guard line.hasPrefix("/// ") else { continue }
                
                let index = line.index(line.startIndex, offsetBy: 4)
                let newLine = line.substring(from: index)
                invocation.buffer.lines[lineIndex] = newLine
                updatedSelections.append(
                    {
                        $0.start = XCSourceTextPosition(line: lineIndex, column: 0)
                        $0.end   = XCSourceTextPosition(line: lineIndex + 1, column: 0)
                        return $0
                    }(XCSourceTextRange()))
            }
        }
        if !updatedSelections.isEmpty {
            invocation.buffer.selections.setArray(updatedSelections)
        }
        completionHandler(nil)
    }