iCloud和iCloud Drive可在使用和不使用iOS 9的情况下为多个设备保存核心数据

I have searched and searched but it is not entirely clear, I haven't programmed much in years, I have to update an old app for a client that will be using iPods iOS 6 and new iPhones with iOS 9 logged into the same iCloud account. I have searched and searched but it is not enti