Convert date from a format to another

DateConverterExtension.swift

extension String {
    
    func convertDateDFormat(from: String = "yyyy-mm-dd", to: String = "EEE dd/mm/yyyy") -> String! {
        
        let dateOriginalFormat = NSDateFormatter()
        dateOriginalFormat.dateFormat = from
        
        let dateDestinationFormat = NSDateFormatter()
        dateDestinationFormat.dateFormat = to
        
        let dateFromString = dateOriginalFormat.dateFromString(self)
        
        let dateFormated = dateDestinationFormat.stringFromDate(dateFromString!)
        
        return dateFormated
        
    }
    
}