Version: 2022.3
  • C#


class in UnityEngine


Implemented in:UnityEngine.CoreModule

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The Caching class lets you manage cached AssetBundles, downloaded using UnityWebRequestAssetBundle.GetAssetBundle().

**Note:** The Cache API is not supported in WebGL because AssetBundles are stored in the browser cache for the WebGL platform. See Also: DownloadHandlerAssetBundle.

using System.Collections;
using UnityEngine;
using System.IO;
using System;
using UnityEngine.Networking;
using System.Collections.Generic;

public class Example : MonoBehaviour { IEnumerator DownloadAndCacheAssetBundle(string uri, string manifestBundlePath) { //Load the manifest AssetBundle manifestBundle = AssetBundle.LoadFromFile(manifestBundlePath); AssetBundleManifest manifest = manifestBundle.LoadAsset<AssetBundleManifest>("AssetBundleManifest");

//Create new cache string today = DateTime.Today.ToLongDateString(); Directory.CreateDirectory(today); Cache newCache = Caching.AddCache(today);

//Set current cache for writing to the new cache if the cache is valid if (newCache.valid) Caching.currentCacheForWriting = newCache;

//Download the bundle Hash128 hash = manifest.GetAssetBundleHash("bundleName"); UnityWebRequest request = UnityWebRequestAssetBundle.GetAssetBundle(uri, hash, 0); yield return request.SendWebRequest(); AssetBundle bundle = DownloadHandlerAssetBundle.GetContent(request);

//Get all the cached versions List<Hash128> listOfCachedVersions = new List<Hash128>(); Caching.GetCachedVersions(, listOfCachedVersions);

if (!AssetBundleContainsAssetIWantToLoad(bundle)) //Or any conditions you want to check on your new asset bundle { //If our criteria wasn't met, we can remove the new cache and revert back to the most recent one Caching.currentCacheForWriting = Caching.GetCacheAt(Caching.cacheCount); Caching.RemoveCache(newCache);

for (int i = listOfCachedVersions.Count - 1; i > 0; i--) { //Load a different bundle from a different cache request = UnityWebRequestAssetBundle.GetAssetBundle(uri, listOfCachedVersions[i], 0); yield return request.SendWebRequest(); bundle = DownloadHandlerAssetBundle.GetContent(request);

//Check and see if the newly loaded bundle from the cache meets your criteria if (AssetBundleContainsAssetIWantToLoad(bundle)) break; } } else { //This is if we only want to keep 5 local caches at any time if (Caching.cacheCount > 5) Caching.RemoveCache(Caching.GetCacheAt(1)); //Removes the oldest user created cache } }

bool AssetBundleContainsAssetIWantToLoad(AssetBundle bundle) { return (bundle.LoadAsset<GameObject>("MyAsset") != null); //this could be any conditional } }

To store up to five cached versions of the same bundle and use the previous caches if your most recent cache becomes invalid, or the downloaded Asset Bundle has a problem, use the following setup.

using System.Collections;
using System.Collections.Generic;
using UnityEngine;
using UnityEngine.Networking;
using System.IO;

public class Example2 : MonoBehaviour { public static class CacheWithPriority { public enum ResolutionType { High, Medium, Low, } static readonly Dictionary<ResolutionType, Cache> ResolutionCaches = new Dictionary<ResolutionType, Cache>();

public static void InitResolutionCaches() { string highResPath = "HighRes"; string medResPath = "MedRes"; string lowResPath = Application.streamingAssetsPath;

//Create cache paths Directory.CreateDirectory(highResPath); Directory.CreateDirectory(medResPath);

//Create the caches and add them to a Dictionary ResolutionCaches.Add(ResolutionType.High, Caching.AddCache(highResPath)); ResolutionCaches.Add(ResolutionType.Medium, Caching.AddCache(medResPath)); ResolutionCaches.Add(ResolutionType.Low, Caching.AddCache(lowResPath)); }

public static void PrioritizeCacheForLoading(ResolutionType resolutionToPrioritize) { //Move cache to the start of the queue Caching.MoveCacheBefore(ResolutionCaches[resolutionToPrioritize], Caching.GetCacheAt(0)); }

public static void SetResolutionCacheForWriting(ResolutionType resolutionToWriteTo) { Caching.currentCacheForWriting = ResolutionCaches[resolutionToWriteTo]; } }

AssetBundle currentTextureAssetBundle; IEnumerator RearrangeCacheOrderExample(string manifestBundlePath) { CacheWithPriority.InitResolutionCaches();

//Load the manifest AssetBundle manifestBundle = AssetBundle.LoadFromFile(manifestBundlePath); AssetBundleManifest manifest = manifestBundle.LoadAsset<AssetBundleManifest>("AssetBundleManifest");

//We know we want to start loading from the Low Resolution Cache CacheWithPriority.PrioritizeCacheForLoading(CacheWithPriority.ResolutionType.Low);

//Load the low res bundle from StreamingAssets UnityWebRequest lowRequest = UnityWebRequestAssetBundle.GetAssetBundle("lowResBundlePath", manifest.GetAssetBundleHash("lowResBundle"), 0); yield return lowRequest; currentTextureAssetBundle = DownloadHandlerAssetBundle.GetContent(lowRequest);

//In the background we can start downloading our higher resolution bundles StartCoroutine(StartDownloadHigherResolutionBundles(manifest));

//Do work with low res bundle while the higher resolutions download... }

IEnumerator StartDownloadHigherResolutionBundles(AssetBundleManifest manifest) { CacheWithPriority.SetResolutionCacheForWriting(CacheWithPriority.ResolutionType.Medium); UnityWebRequest medRequest = UnityWebRequestAssetBundle.GetAssetBundle("medResBundleUrl", manifest.GetAssetBundleHash("medResBundle"), 0); medRequest.SendWebRequest();

while (!medRequest.isDone) yield return null; SwitchTextureBundleTo(CacheWithPriority.ResolutionType.Medium, medRequest);

//Now you'll be using the medium resolution bundle

CacheWithPriority.SetResolutionCacheForWriting(CacheWithPriority.ResolutionType.High); UnityWebRequest highRequest = UnityWebRequestAssetBundle.GetAssetBundle("highResBundleUrl", manifest.GetAssetBundleHash("highResBundle"), 0); highRequest.SendWebRequest();

while (!highRequest.isDone) yield return null; SwitchTextureBundleTo(CacheWithPriority.ResolutionType.High, highRequest);

//Do work with the high resolution bundle now... }

void SwitchTextureBundleTo(CacheWithPriority.ResolutionType typeToSwitchTo, UnityWebRequest request) { //For performance, we tell the Caching system what cache we want it to search first CacheWithPriority.PrioritizeCacheForLoading(typeToSwitchTo); //Unload our current texture bundle currentTextureAssetBundle.Unload(true); //Load the new one from the passed in UnityWebRequest currentTextureAssetBundle = DownloadHandlerAssetBundle.GetContent(request); } }

The ability to have multiple caches allows you to keep several cached version of a particular Asset Bundle. You can use these for things like backups and fallbacks.

This example shows downloading medium resolution and high resolution textures after startup and caching them in their own appropriate caches.

Static Properties

cacheCountReturns the cache count in the cache list.
compressionEnabledControls compression of cache data. Enabled by default.
currentCacheForWritingGets or sets the current cache in which AssetBundles should be cached.
defaultCacheReturns the default cache which is added by Unity internally.
readyReturns true if Caching system is ready for use.

Static Methods

AddCacheAdd a cache with the given path.
ClearAllCachedVersionsRemoves all the cached versions of the given AssetBundle from the cache.
ClearCacheRemoves all AssetBundle content that has been cached by the current application.
ClearCachedVersionRemoves the given version of the AssetBundle.
ClearOtherCachedVersionsRemoves all the cached versions of the AssetBundle from the cache, except for the specified version.
GetAllCachePathsReturns all paths of the cache in the cache list.
GetCacheAtReturns the Cache at the given position in the cache list.
GetCacheByPathReturns the Cache that has the given cache path.
GetCachedVersionsReturns all cached versions of the given AssetBundle.
IsVersionCachedChecks if an AssetBundle is cached.
MarkAsUsedBumps the timestamp of a cached file to be the current time.
MoveCacheAfterMoves the source Cache after the destination Cache in the cache list.
MoveCacheBeforeMoves the source Cache before the destination Cache in the cache list.
RemoveCacheRemoves the Cache from cache list.