- (void)viewDidLoad
{
    [super viewDidLoad];

    // Create a new keychain item instance
    APSKeychainWrapper *keychainItem = [[[APSKeychainWrapper alloc] initWithIdentifier:@"myaccount"
                                                                               service:@"com.appcelerator.service"
                                                                           accessGroup:@"$(AppIdentifierPrefix)com.appcelerator.keychain"
                                                                     accessibilityMode:kSecAttrAccessibleWhenPasscodeSetThisDeviceOnly
                                                                     accessControlMode:kSecAccessControlTouchIDAny
                                                                               options:@{(id)kSecUseOperationPrompt: @"Please authenticate yourself before"}];

    // Implement the APSKeychainWrapperDelegate in your class before
    [keychainItem setDelegate:self];

    // Check existence asynchronously, since the result might be delayed by the user-interacton (e.g. Touch ID)
    [keychainItem exists:^(BOOL success, NSError *error) {
        if (error) {
            NSLog(@"Error checking existence: %@", [error localizedDescription]);
            return;
        }
        
        NSLog(@"Does item exist: %lu", success);
    }];

    // Read
    [keychainItem read];

    // Save
    [keychainItem save:@"my_secret_password"];

    // Update
    [keychainItem update:@"my_new_secret_password"];

    // Reset
    [keychainItem reset];
}

#pragma mark Delegates

- (void)APSKeychainWrapper:(APSKeychainWrapper *)keychainWrapper didSaveValueWithResult:(NSDictionary *)result
{
    // Keychain value saved successfully
}

- (void)APSKeychainWrapper:(APSKeychainWrapper *)keychainWrapper didSaveValueWithError:(NSError *)error
{
    // Keychain value not saved, error occurred
}

- (void)APSKeychainWrapper:(APSKeychainWrapper *)keychainWrapper didReadValueWithResult:(NSDictionary *)result
{
    // Keychain value received successfully
}

- (void)APSKeychainWrapper:(APSKeychainWrapper *)keychainWrapper didReadValueWithError:(NSError *)error
{
    // Keychain value not received, error occurred
}

- (void)APSKeychainWrapper:(APSKeychainWrapper *)keychainWrapper didUpdateValueWithResult:(NSDictionary *)result
{
    // Keychain value updated successfully
}

- (void)APSKeychainWrapper:(APSKeychainWrapper *)keychainWrapper didUpdateValueWithError:(NSError *)error
{
    // Keychain value not updated, error occurred
}

- (void)APSKeychainWrapper:(APSKeychainWrapper *)keychainWrapper didDeleteValueWithResult:(NSDictionary *)result
{
    // Keychain value deleted successfully
}

- (void)APSKeychainWrapper:(APSKeychainWrapper *)keychainWrapper didDeleteValueWithError:(NSError *)error
{
    // Keychain value not deleted, error occurred
}