Question

I wrote these lines in my code:

CFUUIDRef identifier = CFUUIDCreate(NULL);
NSString *identifierString = (NSString*)CFUUIDCreateString(NULL, identifier);
NSLog(@"%@",identifierString);
[self setValue:identifierString forKey:kParamNameDeviceId];

But these lines are getting called every time when the app launches.

Now my question is, how can the following be achieved?

• Create CFUUID.
• Store it in some variable in such a way that, when next time my app starts, it should not create a new CFUUID. It should look for the previously created CFUUID and return it.

In short, I want a CFUUID be created ONCE and used throughout the life of the app (till it gets uninstalled).

Answer 1

Create once. Add it in NSUSerDefaults and check whether you have a UUID stored already before creating one. Simple Pseudo code,

    NSString *CFUUID = nil;

if (![[NSUserDefaults standardUserDefaults] objectForKey:@"UUID"]) {
    //create CFUUDID.

    [[NSUserDefaults standardUserDefaults] setObject:CFUUID forKey:@"UUID"];

}
else
{
    CFUUID = [[NSUserDefaults standardUserDefaults] objectForKey:@"UUID"];
}