Managing catalogs at runtime

By default, the Addressables system manages the catalog automatically at runtime. If you built your application with a remote catalog, the Addressables system automatically checks to see if you have uploaded a new catalog, and, if so, downloads the new version and loads it into memory.

You can load additional catalogs at runtime. For example, you could load a catalog produced by a separate, compatible project to load Addressable assets built by that project. (See Loading Content from Multiple Projects.)

If you want to change the default catalog update behavior of the Addressables stystem, you can turn off the automatic check and check for updates manually. See Updating catalogs.

Loading additional catalogs

Use Addressables.LoadContentCatalogAsync to load additional content catalogs, either from your hosting service or from the local file system. After the operation to load the catalog is finished, you can call any Addressables loading functions using the keys in the new catalog.

If you provide the catalog hash file at the same URL as the catalog, Addressables caches the secondary catalog. When the client application loads the catalog in the future, it only downloads a new version of the catalog if the hash changes.

Once you load a catalog, you cannot unload it. You can, however, update a loaded catalog. You must release the operation handle for the operation that loaded the catalog before updating a catalog. See Updating catalogs for more information.

In general, there is no reason to hold on to the operation handle after loading a catalog. You can release it automatically by setting the autoReleaseHandle parameter to true when loading a catalog, as shown in the following example:

public IEnumerator Start() {
    //Load a catalog and automatically release the operation handle.
    AsyncOperationHandle<IResourceLocator> handle 
        = Addressables.LoadContentCatalogAsync("path_to_secondary_catalog", true);
    yield return handle;

    //...
}

Note

You can use the Catalog Download Timeout property of your Addressables settings to specify a timeout for downloading catalogs.

Updating catalogs

If the catalog hash file is available, Addressables checks the hash when loading a catalog to determine if the version at the provided URL is more recent than the cached version of the catalog. You can turn off the default catalog check, if desired, and call the Addressables.UpdateCatalogs function when you want to update the catalog. If you loaded a catalog manually with LoadContentCatalogAsync, you must release the operation handle before you can update the catalog.

When you call the UpdateCatalog function, all other Addressable requests are blocked until the operation is finished. You can release the operation handle returned by UpdateCatalogs immediately after the operation finishes (or set the autoRelease parameter to true).

If you call UpdateCatalog without providing a list of catalogs, Addressables checks all of the currently loaded catalogs for updates.

IEnumerator UpdateCatalogs() {
    AsyncOperationHandle<List<IResourceLocator>> updateHandle
        = Addressables.UpdateCatalogs();

    yield return updateHandle;
    Addressables.Release(updateHandle);
}

You can also call Addressables.CheckForCatalogUpdates directly to get the list of catalogs that have updates and then perform the update:

IEnumerator CheckCatalogs() {
    List<string> catalogsToUpdate = new List<string>();
    AsyncOperationHandle<List<string>> checkForUpdateHandle 
        = Addressables.CheckForCatalogUpdates();
    checkForUpdateHandle.Completed += op =>
    {
        catalogsToUpdate.AddRange(op.Result);
    };

    yield return checkForUpdateHandle;

    if (catalogsToUpdate.Count > 0) {
        AsyncOperationHandle<List<IResourceLocator>> updateHandle 
            = Addressables.UpdateCatalogs(catalogsToUpdate);
        yield return updateHandle;
        Addressables.Release(updateHandle);
    }

    Addressables.Release(checkForUpdateHandle);
}

Important

If you update a catalog when you have already loaded content from the related AssetBundles, you can encounter conflicts between the loaded AssetBundles and the updated versions. You can enable the Unique Bundle Ids option in your Addressable settings to eliminate the possibility of bundle ID collisions at runtime. However, enabling this option also means that more AssetBundles must typically be rebuilt when you perform a content update. See Content update builds for more information. Another option is to first unload any content and AssetBundles that must be updated, which can be a slow operation.