com.unity.uiextensions/Examples/SerialisationExampleScriptsAndClasses/TestScript.cs

namespace UnityEngine.UI.Extensions.Examples
{
    public class TestScript : MonoBehaviour
    {
        public string testString = "Hello";
        public GameObject someGameObject;
        public string someGameObject_id;
        public TestClass testClass = new TestClass();
        public TestClass[] testClassArray = new TestClass[2];
        [DontSaveField] public Transform TransformThatWontBeSaved;//The [DontSaveField] attribute we wrote ourselves prevents the field from being included in the packed component data

        public void OnSerialize()
        {
            //This is an example of a OnSerialize method, called before a gameobject is packed into serializable form.
            //In this case, the GameObject variable "someGameObject" and those in the testClass and testclass Array instances of TestClass should be reconstructed after loading.
            //Since GameObject (and Transform) references assigned during runtime can't be serialized directly, 
            //we keep a seperate string variable for each GO variable that holds the ID of the GO instead.
            //This allows us to just save the ID instead.

            //This example is one way of dealing with GameObject (and Transform) references. If a lot of those occur in your project,
            //it might be more efficient to go directly into the static SaveLoad.PackComponent method. and doing it there.

            if (someGameObject != null && someGameObject.GetComponent<ObjectIdentifier>())
            {
                someGameObject_id = someGameObject.GetComponent<ObjectIdentifier>().id;
            }
            else
            {
                someGameObject_id = null;
            }

            if (testClassArray != null)
            {
                foreach (TestClass testClass_cur in testClassArray)
                {
                    if (testClass_cur.go != null && testClass_cur.go.GetComponent<ObjectIdentifier>())
                    {
                        testClass_cur.go_id = testClass_cur.go.GetComponent<ObjectIdentifier>().id;
                    }
                    else
                    {
                        testClass_cur.go_id = null;
                    }
                }

            }
        }

        public void OnDeserialize()
        {

            //Since we saved the ID of the GameObject references, we can now use those to recreate the references. 
            //We just iterate through all the ObjectIdentifier component occurences in the scene, compare their id value to our saved and loaded someGameObject id (etc.) value,
            //and assign the component's GameObject if it matches.
            //Note that the "break" command is important, both because it elimitates unneccessary iterations, 
            //and because continuing after having found a match might for some reason find another, wrong match that makes a null reference.

            ObjectIdentifier[] objectsIdentifiers = FindObjectsOfType(typeof(ObjectIdentifier)) as ObjectIdentifier[];

            if (string.IsNullOrEmpty(someGameObject_id) == false)
            {
                foreach (ObjectIdentifier objectIdentifier in objectsIdentifiers)
                {

                    if (string.IsNullOrEmpty(objectIdentifier.id) == false)
                    {
                        if (objectIdentifier.id == someGameObject_id)
                        {
                            someGameObject = objectIdentifier.gameObject;
                            break;
                        }
                    }
                }
            }

            if (testClassArray != null)
            {
                foreach (TestClass testClass_cur in testClassArray)
                {
                    if (string.IsNullOrEmpty(testClass_cur.go_id) == false)
                    {
                        foreach (ObjectIdentifier objectIdentifier in objectsIdentifiers)
                        {
                            if (string.IsNullOrEmpty(objectIdentifier.id) == false)
                            {
                                if (objectIdentifier.id == testClass_cur.go_id)
                                {
                                    testClass_cur.go = objectIdentifier.gameObject;
                                    break;
                                }
                            }
                        }
                    }
                }
            }
        }
    }
}