FCUUID 1.3.1

FCUUID 1.3.1

LangLanguage Obj-CObjective C
License MIT
ReleasedLast Release Oct 2016

Maintained by Fabio Caccamo.




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FCUUID 1.3.1

  • By
  • Fabio Caccamo

iOS UUID library as alternative to the old good UDID and identifierForVendor.
This library provides the simplest API to obtain universally unique identifiers with different levels of persistence.

It's possible to retrieve the UUIDs created for all devices of the same user, in this way with a little bit of server-side help it's possible manage guest accounts across multiple devices easily.

Requirements & dependencies

  • iOS >= 5.0
  • ARC enabled
  • Key-value storage enabled (target / Capabilities / iCloud / Key-value storage)
  • Security.framework
  • UICKeyChainStore
  • (optional) - Key-value storage enabled -> Target / Capabilities / iCloud / Key-value storage enabled if you want to share uuidsOfUserDevices values across multiple devices using the same iCloud account.
  • (optional) - KeyChain sharing enabled (entitlements and provisioning profile) if you need to share the same uuidForDevice / uuidsOfUserDevices values across multiple apps with the same bundle seed.


Manual install:

Optional setup:

It is recommended to do the setup in applicationDidFinishLaunchingWithOptions method.

  • Add an observer to the FCUUIDsOfUserDevicesDidChangeNotification to be notified about uuids of user devices changes.
  • If necessary, migrate from a previously used UUID or UDID using one of the migrations methods listed in the API section (it's recommended to do migration before calling uuidForDevice or uuidsForUserDevices methods). Keep in mind that migration works only if the existing value is a valid uuid and uuidForDevice has not been created yet.
  • Call any class method to enforce iCloud sync.


Get different UUIDs (each one with its own persistency level)

//changes each time (no persistent)
+(NSString *)uuid;

//changes each time (no persistent), but allows to keep in memory more temporary uuids
+(NSString *)uuidForKey:(id<NSCopying>)key;

//changes each time the app gets launched (persistent to session)
+(NSString *)uuidForSession;

//changes each time the app gets installed (persistent to installation)
+(NSString *)uuidForInstallation;

//changes each time all the apps of the same vendor are uninstalled (this works exactly as identifierForVendor)
+(NSString *)uuidForVendor;

//changes only on system reset, this is the best replacement to the good old udid (persistent to device)
+(NSString *)uuidForDevice;
#import "UIDevice+FCUUID.h"
[[UIDevice currentDevice] uuid];

Get the list of UUIDs of user devices

//returns the list of all uuidForDevice of the same user, in this way it's possible manage guest accounts across multiple devices easily
+(NSArray *)uuidsOfUserDevices;

Migrate from a previously stored UUID / UDID
Before migrating an existing value it's recommended to debug it by simply passing commitMigration:NO and logging the returned value.
When you will be ready for committing the migration, use commitMigration:YES.
After the migration, any future call to uuidForDevice will return the migrated value.

//these methods search for an existing UUID / UDID stored in the KeyChain or in UserDefaults for the given key / service / access-group
+(NSString *)uuidForDeviceMigratingValue:(NSString *)value commitMigration:(BOOL)commitMigration;
+(NSString *)uuidForDeviceMigratingValueForKey:(NSString *)key commitMigration:(BOOL)commitMigration;
+(NSString *)uuidForDeviceMigratingValueForKey:(NSString *)key service:(NSString *)service commitMigration:(BOOL)commitMigration;
+(NSString *)uuidForDeviceMigratingValueForKey:(NSString *)key service:(NSString *)service accessGroup:(NSString *)accessGroup commitMigration:(BOOL)commitMigration;

Check if value is a valid UUID

+(BOOL)uuidValueIsValid:(NSString *)uuidValue;


  • yes
  • - no
  • * read notes below
PERSISTS App memory App relaunch Reset Advertising Identifier App reinstall System reboot System upgrade System reset
uuid - - - - - - -
uuidForKey:key - - - - - -
uuidForSession - - - - - -
uuidForInstallation - - -
uuidForVendor - * - -
uuidForDevice **

*(persists only if the user have not uninstalled all apps of the same vendor)

**(persists only if the user restores a device backup which includes also keychain's data)


How can I share the device uuid between two apps?

You must have KeyChain sharing enabled (entitlements and provisioning profile) and your apps identifiers must have the same bundle seed.

What happens if I call uuidForDevice on 2 different devices using same iCloud account and iCloud Keychain?

You will obtain 2 different uuid(s), and if you call uuidsOfUserDevices you will obtain a list containing the uuids of both devices.

When I reboot / upgrade / reset my device system, will device uuid change?

Please check the persistence table above.

Support development




Released under MIT License.