The switching language of unity causes an error: system FormatException:String was not recognized as a valid DateTime.

One , Something's wrong

1.1 The problem background

Recently, when developing multilingual localization （ Simplified Chinese character - Switch back and forth in traditional Chinese ）, This error occurred ：System.FormatException: String was not recognized as a valid DateTime. --> The system format is abnormal ： The string is not recognized as a valid datetime .

It seems that there is a logical error in passing a wrong string to DateTime.Parse(“”) Method as a parameter . What's so strange is No error occurred under the editor , There is no error when the real machine does not switch languages , Only in IOS This error occurs when switching between simple and traditional system languages .

So guess in different language environments DateTime.Now.ToString() The results are different , So there it is 2.1 Test cases for .

1.2 Error log

Error log captured by real machine switching language ：

System.AggregateException: One or more errors occurred. ---> System.FormatException: String was not recognized as a valid DateTime.
  at System.DateTimeParse.Parse (System.String s, System.Globalization.DateTimeFormatInfo dtfi, System.Globalization.DateTimeStyles styles) [0x00000] in <00000000000000000000000000000000>:0 
  at WZC.ActivityManager+<>c__DisplayClass45_0.<GetActivitySwitchConfig>b__0 (WZC.ActivitySwitchConfig e) [0x00000] in <00000000000000000000000000000000>:0 
  at System.Threading.ContextCallback.Invoke (System.Object state) [0x00000] in <00000000000000000000000000000000>:0 
  at System.Threading.ExecutionContext.RunInternal (System.Threading.ExecutionContext executionContext, System.Threading.ContextCallback callback, System.Object state, System.Boolean preserveSyncCtx) [0x00000] in <00000000000000000000000000000000>:0 
  at System.Runtime.CompilerServices.AsyncMethodBuilderCore+MoveNextRunner.Run () [0x00000] in <00000000000000000000000000000000>:0 
  at System.Action.Invoke () [0x00000] in <00000000000000000000000000000000>:0 
  at System.Threading.ContextCallback.Invoke (System.Object state) [0x00000] in <00000000000000000000000000000000>:0 
  at System.Threading.Tasks.AwaitTaskContinuation.RunCallback (System.Threading.ContextCallback callback, System.Object state, System.Threading.Tasks.Task& currentTask) [0x00000] in <00000000000000000000000000000000>:0 
  at System.Threading.Tasks.Task`1[TResult].TrySetResult (TResult result) [0x00000] in <00000000000000000000000000000000>:0 
  at System.Runtime.CompilerServices.AsyncTaskMethodBuilder`1[TResult].Create () [0x00000] in <00000000000000000000000000000000>:0 
  at WZC.ApiHelper..cctor () [0x00000] in <00000000000000000000000000000000>:0 
  at System.Threading.ContextCallback.Invoke (System.Object state) [0x00000] in <00000000000000000000000000000000>:0 
  at System.Threading.ExecutionContext.RunInternal (System.Threading.ExecutionContext executionContext, System.Threading.ContextCallback callback, System.Object state, System.Boolean preserveSyncCtx) [0x00000] in <00000000000000000000000000000000>:0 
  at System.Runtime.CompilerServices.AsyncMethodBuilderCore+MoveNextRunner.Run () [0x00000] in <00000000000000000000000000000000>:0 
  at System.Action.Invoke () [0x00000] in <00000000000000000000000000000000>:0 
  at System.Threading.ContextCallback.Invoke (System.Object state) [0x00000] in <00000000000000000000000000000000>:0 
   --- End of inner exception stack trace ---

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Two , Location problem

2.1 The test case

According to the logic of the game DateTime Usage situation , For the convenience of observing logs Scroll View Components , Put a long one inside Text, The test code and scenario construction effect are as follows ：

using System;
using UnityEngine;
using UnityEngine.UI;

public class ConverTimeError : MonoBehaviour
{
    
    public Text context;
    public Button cunShiJian;
    public Button quShiJian;
    
    void Start()
    {
    
        var strRus = PlayerPrefs.GetString("Hall:RegionGetDate");
        var strRusDate = DateTime.Parse(strRus);
        context.text += " Conversion result :+++" +  strRusDate.Year + "/" + strRusDate.Month+ "/" + strRusDate.Day + ";\n";
        
        cunShiJian.onClick.AddListener(()=>{
    
            context.text += " Save time  :---" + DateTime.Now + ";\n";
            PlayerPrefs.SetString("Hall:RegionGetDate", DateTime.Now.ToString());
            context.text += " Store results :---" +  PlayerPrefs.GetString("Hall:RegionGetDate") + ";\n";
        });
        quShiJian.onClick.AddListener(()=>{
    
            
            context.text += " Take the time  :+++" + DateTime.Now + ";\n";
            var regionGetDateStr = PlayerPrefs.GetString("Hall:RegionGetDate");
            context.text += " Get the result :+++" +  regionGetDateStr + ";\n";
            var regionGetDate = DateTime.Parse(regionGetDateStr);
            context.text += " Get the conversion result :+++" +  regionGetDate.Year + "/" + regionGetDate.Month+ "/" + regionGetDate.Day + ";\n";
        });
    }
}

Use this test case in macOS and IOS The test of switching languages has been carried out on , The result is nothing abnormal , Find out DateTime.Now.ToString() The result is ： month / Japan / year when : branch : second This format .

---

2.2 Find the problem

No problem found in the test case , Then I have to fill the log in the original project , After several twists and turns, it was finally determined that the format of the string with a storage time was Japan / month / year when : branch : second

So the transformation is simulated in the editor year / month / Japan , month / Japan / year and Japan / month / year Time conversion of three formats ：

Debug.Log(" year / month / Japan : " + DateTime.Parse("2022/7/25 13:11:00"));
Debug.Log(" month / Japan / year : " + DateTime.Parse("7/25/2022 13:11:00"));
//  Problematic time format conversion 
Debug.Log(" Japan / month / year : " + DateTime.Parse("25/7/2022 13:11:00")); 

It turns out that ： Japan / month / year Strings in this format really cannot be used DateTime.Parse() Method to convert .

So here comes the new question , In time storage, we use ：DateTime.Now.ToString(), And in the 2.1 We have confirmed in the test cases of DateTime.Now.ToString() The result is ： month / Japan / year when : branch : second This format .

At the same time, it can be determined that the storage time in the game is used DateTime.Now.ToString() This form , This is very puzzling in the logic of the game Japan / month / year How does the format string come out ？

---

3、 ... and , solve the problem

3.1 Try to solve

At first, I used

DateTime.ParseExact(DateTime.Now.ToString(), "yyyy/dd/MM", System.Globalization.CultureInfo.InvariantCulture);

This method is used for format conversion , Because this is the conversion of the specified format , Therefore, according to the above test results, it is not possible .

3.2 solve the problem

Fix the stored code in the format ：

DateTime.Now.ToString("MM/dd/yyyy HH:mm:ss")

Fortunately, there are only a few places in the project DateTime.Now Assignment , It is very convenient to modify . Finally, the test passed .

Encountered such a strange problem , Make a note of , For children's shoes with similar problems .