# RuntimeInitializeOnLoadMethodAttribute

> Use this attribute to get a callback when the runtime is starting up and loading the first scene.

## Definition

* **Type:** Class
* **Namespace:** [UnityEngine](/engine/6000.6/script-reference/unityengine.md)
* **Assembly:** UnityEngine.CoreModule
* **Inherits from:** [PreserveAttribute](/engine/6000.6/script-reference/unityengine/scripting/preserveattribute.md)

```csharp
[AttributeUsage(AttributeTargets.Method, AllowMultiple = false)]
public class RuntimeInitializeOnLoadMethodAttribute : PreserveAttribute
```

## Remarks

Use the various options for [RuntimeInitializeLoadType](/engine/6000.6/script-reference/unityengine/runtimeinitializeloadtype.md) to control when the method is invoked in the startup sequence.

The following list shows the execution order of the [RuntimeInitializeLoadType](/engine/6000.6/script-reference/unityengine/runtimeinitializeloadtype.md) callbacks:

1. Various low level systems are initialized (window, assemblies, gfx etc.)
2. [RuntimeInitializeLoadType.SubsystemRegistration](/engine/6000.6/script-reference/unityengine/runtimeinitializeloadtype/subsystemregistration.md) and [RuntimeInitializeLoadType.AfterAssembliesLoaded](/engine/6000.6/script-reference/unityengine/runtimeinitializeloadtype/afterassembliesloaded.md) callbacks are invoked.
3. More setup (input systems etc.)
4. [RuntimeInitializeLoadType.BeforeSplashScreen](/engine/6000.6/script-reference/unityengine/runtimeinitializeloadtype/beforesplashscreen.md) callback is invoked.
5. First scene starts loading.
6. [RuntimeInitializeLoadType.BeforeSceneLoad](/engine/6000.6/script-reference/unityengine/runtimeinitializeloadtype/beforesceneload.md) callback is invoked. Objects of the scene are loaded but `Awake` hasn't been called yet. All objects are considered inactive.
7. `Awake` and `OnEnable` are invoked on MonoBehaviours.
8. [RuntimeInitializeLoadType.AfterSceneLoad](/engine/6000.6/script-reference/unityengine/runtimeinitializeloadtype/aftersceneload.md) callback is invoked. Objects of the scene are considered fully loaded and setup. Active objects can be found with FindObjectsByType.

The above details are when starting up a Player build. When entering Play mode in the Editor the same invocations are ensured.

The default callback invocation time is [RuntimeInitializeLoadType.AfterSceneLoad](/engine/6000.6/script-reference/unityengine/runtimeinitializeloadtype/aftersceneload.md). The execution order within each of the [RuntimeInitializeLoadType](/engine/6000.6/script-reference/unityengine/runtimeinitializeloadtype.md) callbacks is not guaranteed.

**Note:** Use the [AlwaysLinkAssemblyAttribute](/engine/6000.6/script-reference/unityengine/scripting/alwayslinkassemblyattribute.md) on package or precompiled assemblies that contain one or more methods with the `[RuntimeInitializeOnLoadMethod]` attribute, but which may not contain types used directly or indirectly in any scenes built for the project.

Additional Resources: [Managed code stripping](/engine/6000.6/manual/scripting/compilation-and-code-reload/script-compilation/managed-code-stripping.md)

## Examples

```csharp
// Demonstration of the RuntimeInitializeOnLoadMethod attribute
using UnityEngine;

class MyClass
{
    [RuntimeInitializeOnLoadMethod(RuntimeInitializeLoadType.BeforeSplashScreen)]
    static void OnBeforeSplashScreen()
    {
        Debug.Log("Before SplashScreen is shown and before the first scene is loaded.");
    }

    [RuntimeInitializeOnLoadMethod(RuntimeInitializeLoadType.BeforeSceneLoad)]
    static void OnBeforeSceneLoad()
    {
        Debug.Log("First scene loading: Before Awake is called.");
    }

    [RuntimeInitializeOnLoadMethod(RuntimeInitializeLoadType.AfterSceneLoad)]
    static void OnAfterSceneLoad()
    {
        Debug.Log("First scene loaded: After Awake is called.");
    }

    [RuntimeInitializeOnLoadMethod]
    static void OnRuntimeInitialized()
    {
        Debug.Log("Runtime initialized: First scene loaded: After Awake is called.");
    }
}
```

## Constructors

| Constructor                                                                                                                                                                                                                                     | Description                                                                                                                                            |
| ----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- | ------------------------------------------------------------------------------------------------------------------------------------------------------ |
| [RuntimeInitializeOnLoadMethodAttribute()](/engine/6000.6/script-reference/unityengine/runtimeinitializeonloadmethodattribute/ctor.md#runtimeinitializeonloadmethodattribute\(\))                                                               | Use the [RuntimeInitializeLoadType](/engine/6000.6/script-reference/unityengine/runtimeinitializeloadtype.md) to control when the callback is invoked. |
| [RuntimeInitializeOnLoadMethodAttribute(UnityEngine.RuntimeInitializeLoadType)](/engine/6000.6/script-reference/unityengine/runtimeinitializeonloadmethodattribute/ctor.md#runtimeinitializeonloadmethodattribute\(runtimeinitializeloadtype\)) | Use the [RuntimeInitializeLoadType](/engine/6000.6/script-reference/unityengine/runtimeinitializeloadtype.md) to control when the callback is invoked. |

## Properties

| Property                                                                                                   | Description                              |
| ---------------------------------------------------------------------------------------------------------- | ---------------------------------------- |
| [loadType](/engine/6000.6/script-reference/unityengine/runtimeinitializeonloadmethodattribute/loadtype.md) | Controling the callback invocation time. |

## Inheritance

**Inherited Members:**

* [Attribute.GetCustomAttributes(MemberInfo, Type)](https://learn.microsoft.com/dotnet/api/system.attribute.getcustomattributes#system-attribute-getcustomattributes\(system-reflection-memberinfo-system-type\))
* [Attribute.GetCustomAttributes(MemberInfo, Type, bool)](https://learn.microsoft.com/dotnet/api/system.attribute.getcustomattributes#system-attribute-getcustomattributes\(system-reflection-memberinfo-system-type-system-boolean\))
* [Attribute.GetCustomAttributes(MemberInfo)](https://learn.microsoft.com/dotnet/api/system.attribute.getcustomattributes#system-attribute-getcustomattributes\(system-reflection-memberinfo\))
* [Attribute.GetCustomAttributes(MemberInfo, bool)](https://learn.microsoft.com/dotnet/api/system.attribute.getcustomattributes#system-attribute-getcustomattributes\(system-reflection-memberinfo-system-boolean\))
* [Attribute.IsDefined(MemberInfo, Type)](https://learn.microsoft.com/dotnet/api/system.attribute.isdefined#system-attribute-isdefined\(system-reflection-memberinfo-system-type\))
* [Attribute.IsDefined(MemberInfo, Type, bool)](https://learn.microsoft.com/dotnet/api/system.attribute.isdefined#system-attribute-isdefined\(system-reflection-memberinfo-system-type-system-boolean\))
* [Attribute.GetCustomAttribute(MemberInfo, Type)](https://learn.microsoft.com/dotnet/api/system.attribute.getcustomattribute#system-attribute-getcustomattribute\(system-reflection-memberinfo-system-type\))
* [Attribute.GetCustomAttribute(MemberInfo, Type, bool)](https://learn.microsoft.com/dotnet/api/system.attribute.getcustomattribute#system-attribute-getcustomattribute\(system-reflection-memberinfo-system-type-system-boolean\))
* [Attribute.GetCustomAttributes(ParameterInfo)](https://learn.microsoft.com/dotnet/api/system.attribute.getcustomattributes#system-attribute-getcustomattributes\(system-reflection-parameterinfo\))
* [Attribute.GetCustomAttributes(ParameterInfo, Type)](https://learn.microsoft.com/dotnet/api/system.attribute.getcustomattributes#system-attribute-getcustomattributes\(system-reflection-parameterinfo-system-type\))
* [Attribute.GetCustomAttributes(ParameterInfo, Type, bool)](https://learn.microsoft.com/dotnet/api/system.attribute.getcustomattributes#system-attribute-getcustomattributes\(system-reflection-parameterinfo-system-type-system-boolean\))
* [Attribute.GetCustomAttributes(ParameterInfo, bool)](https://learn.microsoft.com/dotnet/api/system.attribute.getcustomattributes#system-attribute-getcustomattributes\(system-reflection-parameterinfo-system-boolean\))
* [Attribute.IsDefined(ParameterInfo, Type)](https://learn.microsoft.com/dotnet/api/system.attribute.isdefined#system-attribute-isdefined\(system-reflection-parameterinfo-system-type\))
* [Attribute.IsDefined(ParameterInfo, Type, bool)](https://learn.microsoft.com/dotnet/api/system.attribute.isdefined#system-attribute-isdefined\(system-reflection-parameterinfo-system-type-system-boolean\))
* [Attribute.GetCustomAttribute(ParameterInfo, Type)](https://learn.microsoft.com/dotnet/api/system.attribute.getcustomattribute#system-attribute-getcustomattribute\(system-reflection-parameterinfo-system-type\))
* [Attribute.GetCustomAttribute(ParameterInfo, Type, bool)](https://learn.microsoft.com/dotnet/api/system.attribute.getcustomattribute#system-attribute-getcustomattribute\(system-reflection-parameterinfo-system-type-system-boolean\))
* [Attribute.GetCustomAttributes(Module, Type)](https://learn.microsoft.com/dotnet/api/system.attribute.getcustomattributes#system-attribute-getcustomattributes\(system-reflection-module-system-type\))
* [Attribute.GetCustomAttributes(Module)](https://learn.microsoft.com/dotnet/api/system.attribute.getcustomattributes#system-attribute-getcustomattributes\(system-reflection-module\))
* [Attribute.GetCustomAttributes(Module, bool)](https://learn.microsoft.com/dotnet/api/system.attribute.getcustomattributes#system-attribute-getcustomattributes\(system-reflection-module-system-boolean\))
* [Attribute.GetCustomAttributes(Module, Type, bool)](https://learn.microsoft.com/dotnet/api/system.attribute.getcustomattributes#system-attribute-getcustomattributes\(system-reflection-module-system-type-system-boolean\))
* [Attribute.IsDefined(Module, Type)](https://learn.microsoft.com/dotnet/api/system.attribute.isdefined#system-attribute-isdefined\(system-reflection-module-system-type\))
* [Attribute.IsDefined(Module, Type, bool)](https://learn.microsoft.com/dotnet/api/system.attribute.isdefined#system-attribute-isdefined\(system-reflection-module-system-type-system-boolean\))
* [Attribute.GetCustomAttribute(Module, Type)](https://learn.microsoft.com/dotnet/api/system.attribute.getcustomattribute#system-attribute-getcustomattribute\(system-reflection-module-system-type\))
* [Attribute.GetCustomAttribute(Module, Type, bool)](https://learn.microsoft.com/dotnet/api/system.attribute.getcustomattribute#system-attribute-getcustomattribute\(system-reflection-module-system-type-system-boolean\))
* [Attribute.GetCustomAttributes(Assembly, Type)](https://learn.microsoft.com/dotnet/api/system.attribute.getcustomattributes#system-attribute-getcustomattributes\(system-reflection-assembly-system-type\))
* [Attribute.GetCustomAttributes(Assembly, Type, bool)](https://learn.microsoft.com/dotnet/api/system.attribute.getcustomattributes#system-attribute-getcustomattributes\(system-reflection-assembly-system-type-system-boolean\))
* [Attribute.GetCustomAttributes(Assembly)](https://learn.microsoft.com/dotnet/api/system.attribute.getcustomattributes#system-attribute-getcustomattributes\(system-reflection-assembly\))
* [Attribute.GetCustomAttributes(Assembly, bool)](https://learn.microsoft.com/dotnet/api/system.attribute.getcustomattributes#system-attribute-getcustomattributes\(system-reflection-assembly-system-boolean\))
* [Attribute.IsDefined(Assembly, Type)](https://learn.microsoft.com/dotnet/api/system.attribute.isdefined#system-attribute-isdefined\(system-reflection-assembly-system-type\))
* [Attribute.IsDefined(Assembly, Type, bool)](https://learn.microsoft.com/dotnet/api/system.attribute.isdefined#system-attribute-isdefined\(system-reflection-assembly-system-type-system-boolean\))
* [Attribute.GetCustomAttribute(Assembly, Type)](https://learn.microsoft.com/dotnet/api/system.attribute.getcustomattribute#system-attribute-getcustomattribute\(system-reflection-assembly-system-type\))
* [Attribute.GetCustomAttribute(Assembly, Type, bool)](https://learn.microsoft.com/dotnet/api/system.attribute.getcustomattribute#system-attribute-getcustomattribute\(system-reflection-assembly-system-type-system-boolean\))
* [Attribute.Equals(Object)](https://learn.microsoft.com/dotnet/api/system.attribute.equals)
* [Attribute.GetHashCode()](https://learn.microsoft.com/dotnet/api/system.attribute.gethashcode)
* [Attribute.Match(Object)](https://learn.microsoft.com/dotnet/api/system.attribute.match)
* [Attribute.IsDefaultAttribute()](https://learn.microsoft.com/dotnet/api/system.attribute.isdefaultattribute)
* [Attribute.TypeId()](https://learn.microsoft.com/dotnet/api/system.attribute.typeid)