Singleton does not work as expected

I have 2 classes UIController and GameController inherit a generic Singleton class.

Code (csharp):

1.  
2. public class Singleton<T> : MonoBehaviour where T : MonoBehaviour
3. {
4.     static T ins;
5.     public static T Ins { get { return ins; } private set { ins = value; } }
6.     void Awake()
7.     {
8.         if (ins != null && ins != this)
9.         {
10.             Destroy(gameObject);
11.         }
12.         else
13.         {
14.             ins = this as T;
15.             DontDestroyOnLoad(gameObject);
16.         }
17.     }
18. }
19.  

But when I start the game, only GameController is created in the Don'tDestroyOnLoad field and the UIController is not. Where did I do wrong?

 

Here you go:

Code (CSharp):

1.     public class Singleton<T> : MonoBehaviour where T : MonoBehaviour
2.     {
3.         private static T instance = null;
4.         private static readonly Object syncRoot = new Object();
5.  
6.         public static T Instance
7.         {
8.             get
9.             {
10.                 if (instance == null)
11.                 {
12.                     lock (syncRoot)
13.                     {
14.                         if (instance == null)
15.                         {
16.                             instance = FindObjectOfType(typeof(T)) as T;
17.                             if (instance == null)
18.                                 Debug.LogError(
19.                                     "SingletoneBase<T>: Could not found GameObject of type " + typeof(T).Name);
20.                         }
21.                     }
22.                 }
23.  
24.                 return instance;
25.             }
26.         }
27.     }

 

Good stuff @Terraya... and here's my personal favorite.

ULTRA-simple static solution to a GameManager:

https://forum.unity.com/threads/i-need-to-save-the-score-when-the-scene-resets.1168766/#post-7488068

https://gist.github.com/kurtdekker/50faa0d78cd978375b2fe465d55b282b

OR for a more-complex "lives as a MonoBehaviour" solution...

Simple Singleton (UnitySingleton):

Some super-simple Singleton examples to take and modify:

Simple Unity3D Singleton (no predefined data):

https://gist.github.com/kurtdekker/775bb97614047072f7004d6fb9ccce30

Unity3D Singleton with a Prefab (or a ScriptableObject) used for predefined data:

https://gist.github.com/kurtdekker/2f07be6f6a844cf82110fc42a774a625

These are pure-code solutions, do not put anything into any scene, just access it via .Instance!

If it is a GameManager, when the game is over, make a function in that singleton that Destroys itself so the next time you access it you get a fresh one, something like:

Code (csharp):

1. public void DestroyThyself()
2. {
3.    Destroy(gameObject);
4.    Instance = null;    // because destroy doesn't happen until end of frame
5. }

There are also lots of Youtube tutorials on the concepts involved in making a suitable GameManager, which obviously depends a lot on what your game might need.

And if you really insist on barebones C# singleton, here's a Highlander:

https://gist.github.com/kurtdekker/b860fe6734583f8dc70eec475b1e7163

Also, for OP, if you post a code snippet, ALWAYS USE CODE TAGS:

How to use code tags: https://forum.unity.com/threads/using-code-tags-properly.143875/

You may edit your post above.

 

Thank you so much. Both answers are great answers for me.