Some of the built-in features of Unity automatically use serialization. These are outlined below.
See the documentation on Script Serialization for further information.
Unity uses serialization to load and save Scenes, Assets, and AssetBundles to and from your computer’s hard drive. This includes data saved in your own scripting API objects such as MonoBehaviour components and ScriptableObjects.
This happens in the Editor’s Play Mode and Edit Mode.
When you view or change the value of a GameObject’s component field in the Inspector window, Unity serializes this data and then displays it in the Inspector window. The Inspector window does not communicate with the Unity Scripting API when it displays the values of a field. If you use properties in your script, any of the property getters and setters are never called when you view or change values in the Inspector windows as Unity serializes the Inspector window fields directly.
When you change and save a script, Unity reloads all the currently loaded script data. It first stores all serializable variables in all loaded scripts, and after loading the scripts restores them. All data that is not serializable is lost after the script is reloaded.
This affects all Editor windows, as well as all MonoBehaviours in the project. Unlike other cases of serialization in Unity, private fields are serialized by default when reloading, even if they don’t have the ‘SerializeField’ attribute.
In the context of serialization, a Prefab is the serialized data of one or more GameObjects and components. A Prefab instance contains a reference to both the Prefab source and a list of modifications to it. The modifications are what Unity needs to do to the Prefab source to create that particular Prefab instance.
The Prefab instance only exists while you edit your project in the Unity Editor. During the project build, the Unity Editor instantiates a GameObject from its two sets of serialization data: the Prefab source and the Prefab instance’s modifications.
When you call Instantiate on anything that exists in a Scene, such as a Prefab or a GameObjects, Unity serializes it. This happens both at runtime and in the Editor. Everything that derives from UnityEngine.Object can be serialized.
Unity then creates a new GameObject and deserializes the data onto the new GameObject. Next, Unity runs the same serialization code in a different variant to report which other UnityEngine.Objects
are being referenced. It checks all referenced UnityEngine.Objects
to see if they are part of the data being instantiated. If the reference points to something “external”, such as a Texture, Unity keeps that reference as it is. If the reference points to something “internal”, such as a child GameObject, Unity patches the reference to the corresponding copy.
Resource.GarbageCollectSharedAssets()
is the native Unity garbage collector and performs a different function to the standard C# garbage collector. It runs after you load a Scene and checks for objects (like textures) that are no longer referenced and unloads them safely. The native Unity garbage collector runs the serializer in a variation in which objects report all references to external UnityEngine.Objects
. This is how Textures that were used by one scene are unloaded in the next.
• 2017–05–15 Page published with editorial review
Did you find this page useful? Please give it a rating:
Thanks for rating this page!
What kind of problem would you like to report?
Is something described here not working as you expect it to? It might be a Known Issue. Please check with the Issue Tracker at issuetracker.unity3d.com.
Thanks for letting us know! This page has been marked for review based on your feedback.
If you have time, you can provide more information to help us fix the problem faster.
Provide more information
You've told us this page needs code samples. If you'd like to help us further, you could provide a code sample, or tell us about what kind of code sample you'd like to see:
You've told us there are code samples on this page which don't work. If you know how to fix it, or have something better we could use instead, please let us know:
You've told us there is information missing from this page. Please tell us more about what's missing:
You've told us there is incorrect information on this page. If you know what we should change to make it correct, please tell us:
You've told us this page has unclear or confusing information. Please tell us more about what you found unclear or confusing, or let us know how we could make it clearer:
You've told us there is a spelling or grammar error on this page. Please tell us what's wrong:
You've told us this page has a problem. Please tell us more about what's wrong:
Thanks for helping to make the Unity documentation better!
When you visit any website, it may store or retrieve information on your browser, mostly in the form of cookies. This information might be about you, your preferences or your device and is mostly used to make the site work as you expect it to. The information does not usually directly identify you, but it can give you a more personalized web experience. Because we respect your right to privacy, you can choose not to allow some types of cookies. Click on the different category headings to find out more and change our default settings. However, blocking some types of cookies may impact your experience of the site and the services we are able to offer.
More information
These cookies enable the website to provide enhanced functionality and personalisation. They may be set by us or by third party providers whose services we have added to our pages. If you do not allow these cookies then some or all of these services may not function properly.
These cookies allow us to count visits and traffic sources so we can measure and improve the performance of our site. They help us to know which pages are the most and least popular and see how visitors move around the site. All information these cookies collect is aggregated and therefore anonymous. If you do not allow these cookies we will not know when you have visited our site, and will not be able to monitor its performance.
These cookies may be set through our site by our advertising partners. They may be used by those companies to build a profile of your interests and show you relevant adverts on other sites. They do not store directly personal information, but are based on uniquely identifying your browser and internet device. If you do not allow these cookies, you will experience less targeted advertising. Some 3rd party video providers do not allow video views without targeting cookies. If you are experiencing difficulty viewing a video, you will need to set your cookie preferences for targeting to yes if you wish to view videos from these providers. Unity does not control this.
These cookies are necessary for the website to function and cannot be switched off in our systems. They are usually only set in response to actions made by you which amount to a request for services, such as setting your privacy preferences, logging in or filling in forms. You can set your browser to block or alert you about these cookies, but some parts of the site will not then work. These cookies do not store any personally identifiable information.