程序里如何获得AppIdentifierPrefix | iOS开发讨论区

+ (NSString *)bundleSeedID {
    NSDictionary *query = [NSDictionary dictionaryWithObjectsAndKeys:
                           kSecClassGenericPassword, kSecClass,
                           @"bundleSeedID", kSecAttrAccount,
                           @"", kSecAttrService,
                           (id)kCFBooleanTrue, kSecReturnAttributes,
                           nil];
    CFDictionaryRef result = nil;
    OSStatus status = SecItemCopyMatching((CFDictionaryRef)query, (CFTypeRef *)&result);
    if (status == errSecItemNotFound)
        status = SecItemAdd((CFDictionaryRef)query, (CFTypeRef *)&result);
    if (status != errSecSuccess)
        return nil;
    NSString *accessGroup = [(NSDictionary *)result objectForKey:kSecAttrAccessGroup];
    NSArray *components = [accessGroup componentsSeparatedByString:@"."];
    NSString *bundleSeedID = [[components objectEnumerator] nextObject];
    CFRelease(result);
    return bundleSeedID;
}