iOS10.3 beta2 Keychain Autodelete Workaround

KeychainTest.m

- (BOOL)saveToKeychain {
    NSData *passwordData = [@"myPassword" dataUsingEncoding:NSUTF8StringEncoding];
    /* Try to save to the keychain */
    NSMutableDictionary *dictionary = [NSMutableDictionary dictionaryWithCapacity:3];
    [dictionary setObject:(__bridge id)kSecClassGenericPassword forKey:(__bridge id)kSecClass];
    [dictionary setObject:@"myService" forKey:(__bridge id)kSecAttrService];
    [dictionary setObject:@"myAccount" forKey:(__bridge id)kSecAttrAccount];
    /* Use the kSecAttrAccessGroupToken access group constant*/
    [dictionary setObject:(__bridge NSString * _Nullable)(kSecAttrAccessGroupToken) forKey:(__bridge id)kSecAttrAccessGroup];
    [dictionary setObject:passwordData forKey:(__bridge id)kSecValueData];
    
    OSStatus status = SecItemAdd((__bridge CFDictionaryRef)dictionary, NULL);
    if (status != errSecSuccess) {
        NSLog(@"Failed to save to keychain");
        return NO;
    } else {
        NSLog(@"Successfully saved password to keychain");
        return YES;
    }
}

- (NSString *)fetchFromKeychain {
    /* Try to fetch from the keychain */
    NSMutableDictionary *dictionary = [NSMutableDictionary dictionaryWithCapacity:3];
    [dictionary setObject:(__bridge id)kSecClassGenericPassword forKey:(__bridge id)kSecClass];
    [dictionary setObject:@"myService" forKey:(__bridge id)kSecAttrService];
    [dictionary setObject:@"myAccount" forKey:(__bridge id)kSecAttrAccount];
    /* Use the kSecAttrAccessGroupToken access group constant*/
    [dictionary setObject:(__bridge NSString * _Nullable)(kSecAttrAccessGroupToken) forKey:(__bridge id)kSecAttrAccessGroup];
    [dictionary setObject:@YES forKey:(__bridge id)kSecReturnData];
    [dictionary setObject:(__bridge id)kSecMatchLimitOne forKey:(__bridge id)kSecMatchLimit];
    
    NSString *password;
    CFTypeRef result = NULL;
    OSStatus status = SecItemCopyMatching((__bridge CFDictionaryRef)dictionary, &result);
    if (status != errSecSuccess) {
        NSLog(@"Error fetching from keychain");
    } else {
        NSData *passwordData = (__bridge_transfer NSData *)result;
        password = [[NSString alloc] initWithData:passwordData encoding:NSUTF8StringEncoding];
        NSLog(@"Got password from keychain: %@", password);
    }
    
    return password;
}

@laoyur It seems as though keychain entries continue to persist after app uninstall.

The behaviour experienced in the iOS 10.3 beta does not seem to have made it into the public releases.

Also, according to this reply: https://forums.developer.apple.com/thread/72271#224455 it seems as though the kSecAttrAccessGroup access group identifier was never meant to be written to from normal apps, only read from. So, this code should no longer be relied on.