Singleton mode in unity

Encountered a hole in the simplest singleton pattern ... Here is a record of , In case you forget again

General single thread singleton mode , You can use common methods or attributes to implement global access points , Here, I use the public method

/// <summary>
    ///  Implementation of single thread and single instance mode 
    /// </summary>
    public class Singleton
    {
        //  Define a static variable to hold the instance of the class 
        private static Singleton uniqueInstance;

        //  Constructor private , Prevent the outside world from creating such instances 
        private Singleton()
        {
        }

        /// <summary>
        ///  Defining a public method provides a global access point , You can also define public properties to provide global access points 
        /// </summary>
        /// <returns></returns>
        public static Singleton GetInstance()
        {
            //  Determine whether class instances exist , Create if it does not exist , Otherwise go straight back to 
            if (uniqueInstance == null)
            {
                uniqueInstance = new Singleton();
            }
            return uniqueInstance;
        }
    }

If you want to support multi-threaded access , Then add the thread lock in the method of obtaining the instance （lock）, The specific code will not be written

And then say , The problem I have

/// <summary>
    ///  Implementation of single thread and single instance mode 
    /// </summary>
    public class Singleton ：MonoBehaviour
    {
        //  Define a static variable to hold the instance of the class 
        private static Singleton uniqueInstance;

        //  Constructor private , Prevent the outside world from creating such instances 
        private Singleton()
        {
        }

        /// <summary>
        ///  Defining a public method provides a global access point , You can also define public properties to provide global access points 
        /// </summary>
        /// <returns></returns>
        public static Singleton GetInstance()
        {
            //  Determine whether class instances exist , Create if it does not exist , Otherwise go straight back to 
            if (uniqueInstance == null)
            {
                uniqueInstance = new Singleton();
            }
            return uniqueInstance;
        }
    }

I wrote a single example , And then inherit from MonoBehaviour, Then there are some data and code , It's not specifically written here , Then the problem is ： Every time the data is stored in the dictionary or field of this class , It will become empty the next time it is called .

Pass through the code breakpoints and debug Debugging of , After finding the stored data , The data can be seen and saved , But then call GetInstance（） Method to get an instance , The data will be cleared ,uniqueInstance Will turn into null, Even if you are saying uniqueInstance Field time , Instantiate it , It will also become null

What are the specific reasons , I have no definite answer , This problem can only be avoided by debugging , See the big guy know what the reason is , Can also give this dish chicken answer .

I used two methods here , In succession MonoBehaviour Implementation of the singleton

The first one is , Directly in Awake（） Method , Then the public method returns the class directly , Why not assign values to public methods , Because static methods cannot be used this keyword

/// <summary>
    ///  Implementation of single thread and single instance mode 
    /// </summary>
    public class Singleton ：MonoBehaviour
    {
        //  Define a static variable to hold the instance of the class 
        private static Singleton uniqueInstance;

        //  Constructor private , Prevent the outside world from creating such instances 
        private Singleton()
        {
        }
        private void Awake()
        {
        uniqueInstance = this;
        }


        /// <summary>
        ///  Defining a public method provides a global access point , You can also define public properties to provide global access points 
        /// </summary>
        /// <returns></returns>
        public static Singleton GetInstance()
        {
            return uniqueInstance;
        }
    }

The second is to modify the processing when the instance is empty , It's no longer new new One , Instead, look in the scene , Add if not , Then return the found result or the added script

/// <summary>
    ///  Implementation of single thread and single instance mode 
    /// </summary>
    public class Singleton ：MonoBehaviour
    {
        //  Define a static variable to hold the instance of the class 
        private static Singleton uniqueInstance;

        //  Constructor private , Prevent the outside world from creating such instances 
        private Singleton()
        {
        }

        /// <summary>
        ///  Defining a public method provides a global access point , You can also define public properties to provide global access points 
        /// </summary>
        /// <returns></returns>
        public static Singleton GetInstance()
        {
        if (uniqueInstance== null)
        {
            // If uniqueInstance It's empty , Just look for instances of this class in the scenario 
            uniqueInstance= FindObjectOfType(typeof(Singleton)) as Singleton;
            // If uniqueInstance It's still empty , Just create an empty object and add this class 
            if (uniqueInstance== null)
            {
                GameObject obj = new GameObject();
                uniqueInstance= obj.AddComponent<Singleton>();
            }
        }
            return uniqueInstance;
        }
    }

Guess from two solutions above ,unity Hang on the class instantiated by the script , And direct new The classes are different , Cannot recognize each other