# GetExistingSystem

> Return a handle to an existing instance of a system of type T in this World.

## Definition

* **Type:** Method
* **Namespace:** [Unity.Entities](/engine/7000.0/script-reference/unity/entities.md)
* **Assembly:** UnityEngine.EntitiesModule

## GetExistingSystem\<T>()

Return a handle to an existing instance of a system of type `T` in this World.

```csharp
public SystemHandle GetExistingSystem<T>() where T : ComponentSystemBase
```

### Returns

| Type                                                                           | Description                                                                                                                 |
| ------------------------------------------------------------------------------ | --------------------------------------------------------------------------------------------------------------------------- |
| [SystemHandle](/engine/7000.0/script-reference/unity/entities/systemhandle.md) | A handle to the existing instance of system type `T` in this World. If no such instance exists, the method returns default. |

## GetExistingSystem(Type)

Return a handle to an existing instance of a system of type `type` in this World. Prefer the version that takes a SystemTypeIndex where possible to avoid unnecessary reflection.

```csharp
public SystemHandle GetExistingSystem(Type type)
```

### Parameters

**** (\[Type]\(https\://learn.microsoft.com/dotnet/api/system.type)): The system type

### Returns

| Type                                                                           | Description                                                                                                                    |
| ------------------------------------------------------------------------------ | ------------------------------------------------------------------------------------------------------------------------------ |
| [SystemHandle](/engine/7000.0/script-reference/unity/entities/systemhandle.md) | A handle to the existing instance of system type `type` in this World. If no such instance exists, the method returns default. |

## GetExistingSystem(SystemTypeIndex)

Return a handle to an existing instance of a system of type `type` in this World. This version avoids unnecessary reflection.

```csharp
public SystemHandle GetExistingSystem(SystemTypeIndex type)
```

### Parameters

**** (\[SystemTypeIndex]\(/engine/7000.0/script-reference/unity/entities/systemtypeindex)): The system type

### Returns

| Type                                                                           | Description                                                                                                                    |
| ------------------------------------------------------------------------------ | ------------------------------------------------------------------------------------------------------------------------------ |
| [SystemHandle](/engine/7000.0/script-reference/unity/entities/systemhandle.md) | A handle to the existing instance of system type `type` in this World. If no such instance exists, the method returns default. |