# Spawner
This component allows to instantiate needed amount of copies of certain gameobject, in certain spawn point (or points, randomly) with certain time period.
{% hint style="info" %}
This could be useful for spawning AI enemies or NPCs in some game area.
{% endhint %}
### How to use
For faster experience, you can use Spawner prefab in `Assets/Heroic Engine/Prefabs/Gameplay` directory, drag onto your scene and just change some parameters in inspector if needed.
Spawner prefab
This sample spawner will spawn example object presented in the same folder. This object is just a cube with Rigidbody and [LifetimeObject](https://heroicsolo.gitbook.io/heroic-engine/basics/useful-components/lifetimeobject) component which returns this object back to pool after certain amount of time.
### Parameters in inspector
Spawner in inspector
**Object Prefab** – prefab that will be spawned by this spawner. In case if it's PooledObject, it will be got from [PoolSystem](https://heroicsolo.gitbook.io/heroic-engine/basics/engine-utilities/poolsystem).
**Spawn Points** – points where these objects can be spawned (if more than 1 point assigned, they will spawn randomly on given points)
**Launch Mode** – in which way this spawner will be activated.
There are 3 options:
* None (spawner can be activated only via its Launch method)
* At Start (spawner will be activated automatically at start)
* On Trigger Enter (spawner can be activated if collider with appropriate layer enters this spawner trigger zone). Layer can be selected in appropriate field like shown below:
Trigger layer selection
**Start Spawn Delay** – how much time spawner waits before starting spawn process.
**Spawn Period** – time period between spawn waves.
**Spawn Count** – how much objects should be spawned.
***
### Available methods
```csharp
public void Launch()
```
*This method launches spawning process.*
***
```csharp
public void Stop()
```
*This method stops spawning process.*
***
```csharp
public void RemoveSpawnedObjects()
```
*This method destroys all objects spawned by this spawner (if that objects were pooled, they return back to poll).*
***
```csharp
public void SetSpawnPeriod(float period)
```
*This method sets spawn period (in seconds).*
***
```csharp
public void SetSpawnObjectPrefab(GameObject prefab)
```
*This method sets spawn object prefab. If this prefab is inherited from PooledObject, it will be pooled via PoolSystem.*
***
```csharp
public void SetSpawnCallback(Action spawnCallback)
```
*This method sets a certain action which will be invoked each time when object will be spawned.*
***
```csharp
public void SetSpawnEndCallback(Action spawnEndCallback)
```
*This method sets a certain action which will be invoked in the end of whole spawning process.*
