How convert Array String in Data for PropertyList?

I should convert this array String "eventi" to data to pass it to a empty property list.
Is there any way?
Here my code...
In the function I am using FileManager create file at Path but in the content section if I insert the Event Array as Data it gives me a crash

var documentsDirectoryURL : URL {
            return try! FileManager.default.url(for: .documentDirectory, in: .userDomainMask, appropriateFor: nil, create: false)
        let fileURL = documentsDirectoryURL.appendingPathComponent(String(format: "\(settings.stringa_valore_Giorno) \(settings.nome_Mese) \(settings.nome_Anno) Lista_Eventi.plist"))
    self.incrementa_App += 1
    self.eventi2.updateValue(String(format: "\(self.incrementa_App)°"), forKey: titolo)
    for (key, value) in eventi2 {
        eventi.append("\(key), \(value)")
        if let _ = try? fileURL.checkResourceIsReachable()  {
            do {
                let data = try eventi.unique(), format: .binary, options: 0)
                //    print(eventi.unique())
                try? data.write(to: fileURL)
            } catch {
            print("file exists ")
        }else {

            FileManager.default.createFile(atPath: fileURL.path, contents: eventi as! Data?, attributes: nil)
            print("file not exists")