Check out example codes for "playerprefs not working on android". It will help you in understanding the concepts better.

Code Example 1

// Make sure that it has a default value, like 0 for example

public float Highscore;

public void Start()
 {
     Highscore = PlayerPrefs.GetFloat("HighScore", 0); // like this
 }


public void Start()
 {
     Highscore = PlayerPrefs.GetFloat("HighScore"); // not like this
 }

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