How to get unique id in iOS device?

Question

I have used mac address to identify iOS devices in server side. When run my application with iOS 7 unable to retrieve the correct mac address. Alternately i used

Answer 1

The best way to get the device id is identifierForVendor

UIDevice *device = [UIDevice currentDevice];

NSString  *currentDeviceId = [[device identifierForVendor]UUIDString];

UPDATE

For Swift 4.1 use

UIDevice.current.identifierForVendor?.uuidString