Get a unique device ID

[[[UIDevice currentDevice] identifierForVendor] UUIDString];
according to the supplier distribution APP, APP after unloading heavy equipment, regenerates.
You need to use the keychain storage complexes.

YLKeyChainStore @interface: the NSObject
/ ** save data to a keychain * /

• (void) Save: (NSString *) Data-Service: (ID) Data;
  / ** load data from the key string * /
• (the above mentioned id) the Load: (NSString *) Service;
  / ** * Delete data /
• (void)deleteKeyData:(NSString*)service;
  /** 获取UUID*/
• (NSString *)getUUIDByKeyChain;
  @end

/ ** obtain data by key * /

• (NSMutableDictionary)getKeychainQuery:(NSString)service {
  service = [self handleServiceKeyWith:service];
  return[NSMutableDictionary dictionaryWithObjectsAndKeys:
  (id)kSecClassGenericPassword,(id)kSecClass,
  service,(id)kSecAttrService,
  service,(id)kSecAttrAccount,
  (id)kSecAttrAccessibleAfterFirstUnlock,(id)kSecAttrAccessible,
  nil];
  }

• (NSString)handleServiceKeyWith:(NSString)service {
  return [NSString stringWithFormat:@"%@%@",AppBundleID(),service];
  }

• (void)save:(NSString)service data:(id)data{
  //Get search dictionary
  NSMutableDictionarykeychainQuery = [self getKeychainQuery:service];
  //Delete old item before add new item
  SecItemDelete((CFDictionaryRef)keychainQuery);
  //Add new object to searchdictionary(Attention:the data format)
  [keychainQuery setObject:[NSKeyedArchiver archivedDataWithRootObject:data]forKey:(id)kSecValueData];
  //Add item to keychain with the searchdictionary
  SecItemAdd((CFDictionaryRef)keychainQuery,NULL);
  }

• (id)load:(NSString)service {
  id ret =nil;
  NSMutableDictionarykeychainQuery = [self getKeychainQuery:service];
  //Configure the search setting
  //Since in our simple case we areexpecting only a single attribute to be returned (the password) wecan set the attribute kSecReturnData to kCFBooleanTrue
  [keychainQuery setObject:(id)kCFBooleanTrue forKey:(id)kSecReturnData];
  [keychainQuery setObject:(id)kSecMatchLimitOne forKey:(id)kSecMatchLimit];
  CFDataRef keyData =NULL;
  if(SecItemCopyMatching((CFDictionaryRef)keychainQuery,(CFTypeRef)&keyData) ==noErr){
  @try{
  ret =[NSKeyedUnarchiver unarchiveObjectWithData:(__bridge NSData*)keyData];
  }@catch(NSException e) {
  NSLog(@"Unarchiveof %@ failed: %@",[self handleServiceKeyWith:service], e);
  }@finally{
  }
  }
  if(keyData)
  CFRelease(keyData);
  return ret;
  }

• (void)deleteKeyData:(NSString)service {
  NSMutableDictionarykeychainQuery = [self getKeychainQuery:service];
  SecItemDelete((CFDictionaryRef)keychainQuery);
  }

/ ** Gets UUID * /

• (NSString ) getUUIDByKeyChain {
  NSString key = @ "uuid";
  // prefix key is your best BundleID
  NSString strUUID = (NSString ) [YLKeyChainStore the Load: key];
  // the first implementation of the method, uuid is empty
  if ([strUUID as isEqualToString: @ ""] || strUUID!)
  {
  strUUID = [[[currentDevice the UIDevice] identifierForVendor] UUIDString];
  // save the uuid to Keychain
  [YLKeyChainStore save: Key Data: strUUID];
  }
  return strUUID;
  }