# Topic preferences

The Batch iOS SDK allows you to:

* Add or remove topic preferences from a user profile (the profile is created automatically if it doesn’t already exist).
* Partially update topic preferences within a user profile.

> Requires SDK 3.3+

Here’s how to update topic preferences:

{% tabs %}
{% tab title="Swift" %}

```swift
BatchProfile.editor { editor in
    try? editor.setTopicPreferences(["technology", "finance"]) // Null to erase
    // Alternatively, partially update them with:
    try? editor.addToTopicPreferences(["investing"])
    try? editor.removeFromTopicPreferences(["travel"])
    // If you prefer to use BatchProfile.editor() with local variable instead of using a closure,
    // remember to use editor.save() afterwards so that the changes are taken into account.
}
```

{% endtab %}

{% tab title="Objective-C" %}

```objectivec
// This requires to have a custom user ID registered by calling the `identify` method beforehand.
[BatchProfile editWithBlock:^(BatchProfileEditor * _Nonnull editor) {
     NSError *error = nil;
     [editor setTopicPreferences:@[@"technology", @"finance"] error:&error];
     // Alternatively, partially update them with:
     [editor addToTopicPreferences:@[@"investing"] error:&error];
     [editor removeFromTopicPreferences:@[@"travel"] error:&error];
     // If you prefer to use [BatchProfile editor] instead of `editWithBlock`,
     // remember to use [editor save] afterwards so that the changes are taken into account.
}];
```

{% endtab %}
{% endtabs %}

{% hint style="info" %}
**Note**: Topics must be a valid List of String not longer than 25 items. String should be made of letters, numbers or underscores (\[a-z0-9\_]) and can't be longer than 300 characters.
{% endhint %}


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