How to preserve identifierForVendor in ios after uninstalling ios app on device?

Question

I am developing an iOS app which calls web-service for login and at that time i send login credentials to web server along with vendor identifier (identifierForVendor),to identify device uniquely for those credentials.So user can have only one device and one credential.

I got identifierForVendor with

NSString *uuid = [[UIDevice currentDevice] identifierForVendor].UUIDString

This identifier will then store in database of web server and also in device database.Next time when user opens application and will try to download data from web server firstly local identifierForVendor on users device will compare with identifier stored on web server.

Problem occurs when user uninstall app and reinstall it, I found that identifierForVendor is changed. So user cannot proceed further.

I read apple documentation UIDevice Documentation

As mention there, if all app from same vendor uninstalls from device then at time of new installation of any app from that vendor will take new identifierForVendor.

So how to deal with this in my case ?

Answer 1

You may keep it in KeyChain

-(NSString *)getUniqueDeviceIdentifierAsString
{

 NSString *appName=[[[NSBundle mainBundle] infoDictionary] objectForKey:(NSString*)kCFBundleNameKey];

 NSString *strApplicationUUID = [SSKeychain passwordForService:appName account:@"incoding"];
 if (strApplicationUUID == nil)
 {
    strApplicationUUID  = [[[UIDevice currentDevice] identifierForVendor] UUIDString];
    [SSKeychain setPassword:strApplicationUUID forService:appName account:@"incoding"];
 }

 return strApplicationUUID;
}