gistfile1.txt

public class FacebookPay : MonoBehaviour{
		
	public string ProductURL;
 
	public int Quantity;
 
	void OnMouseDown()
	{
 		#if !UNITY_EDITOR
  		FB.Canvas.Pay(product: ProductURL,
  		              action: "purchaseitem",
  		              quantity: 1,
  		              callback: PayCallback);
 		#else
 			MockResponse();
 		#endif
	}
 
	void MockResponse()
	{
		 Invoke("GiveItem",1.5f);
	}
 
	void PayCallback(FBResult result)
	{
 		if (result != null) 
 		{
 			var response = Json.Deserialize(result.Text) as Dictionary<string, object>;
 			if(Convert.ToString(response["status"]) == "completed")
 			{
 				GiveItem();
 			}
 			else
 			{
 				// Payment Failed
 			}
		}
	}
	
	void GiveItem()
	{
	 // Implement your give item here
	}
	
	}