Encountered a very strange problem with Unity

I instantiated 3 button buttons and set the first button to be selected in the event system. When I press the Click button Removed three buttons and re instantiated them, and set the third button selected in the event system, but a strange thing happened. The event system selected was set to effort, EventSystem. current. SetSelectedGameObject (AllUIs. GetChild (2). getObject); This line of code did not work, which is really strange. I don't know why this problem occurred. I need help, who can help me.

 

maybe it happens as you are clicking the button (almost) at the same time as the code executes?
could test that by calling the problem line, setselected with a few frames delay (using coroutine for example)

 

Thank you for your reply. I'll give it a try.

 

I just tried it out and there is still this issue. It's really strange. I really hope the Unity development team can take a look at this issue.

 

You don't need the "Unity development team," you almost certainly just wrote a bug. Here's how you can track it down:

Time to start debugging! Here is how you can begin your exciting new debugging adventures:

You must find a way to get the information you need in order to reason about what the problem is.

Once you understand what the problem is, you may begin to reason about a solution to the problem.

What is often happening in these cases is one of the following:

- the code you think is executing is not actually executing at all
- the code is executing far EARLIER or LATER than you think
- the code is executing far LESS OFTEN than you think
- the code is executing far MORE OFTEN than you think
- the code is executing on another GameObject than you think it is
- you're getting an error or warning and you haven't noticed it in the console window

To help gain more insight into your problem, I recommend liberally sprinkling

Debug.Log()

statements through your code to display information in realtime.

Doing this should help you answer these types of questions:

- is this code even running? which parts are running? how often does it run? what order does it run in?
- what are the names of the GameObjects or Components involved?
- what are the values of the variables involved? Are they initialized? Are the values reasonable?
- are you meeting ALL the requirements to receive callbacks such as triggers / colliders (review the documentation)

Knowing this information will help you reason about the behavior you are seeing.

You can also supply a second argument to Debug.Log() and when you click the message, it will highlight the object in scene, such as

Debug.Log("Problem!",this);

If your problem would benefit from in-scene or in-game visualization, Debug.DrawRay() or Debug.DrawLine() can help you visualize things like rays (used in raycasting) or distances.

You can also call Debug.Break() to pause the Editor when certain interesting pieces of code run, and then study the scene manually, looking for all the parts, where they are, what scripts are on them, etc.

You can also call GameObject.CreatePrimitive() to emplace debug-marker-ish objects in the scene at runtime.

You could also just display various important quantities in UI Text elements to watch them change as you play the game.

Visit Google for how to see console output from builds. If you are running a mobile device you can also view the console output. Google for how on your particular mobile target, such as this answer for iOS: https://forum.unity.com/threads/how-to-capturing-device-logs-on-ios.529920/ or this answer for Android: https://forum.unity.com/threads/how-to-capturing-device-logs-on-android.528680/

If you are working in VR, it might be useful to make your on onscreen log output, or integrate one from the asset store, so you can see what is happening as you operate your software.

Another useful approach is to temporarily strip out everything besides what is necessary to prove your issue. This can simplify and isolate compounding effects of other items in your scene or prefab.

If your problem is with OnCollision-type functions, print the name of what is passed in!

Here's an example of putting in a laser-focused Debug.Log() and how that can save you a TON of time wallowing around speculating what might be going wrong:

https://forum.unity.com/threads/coroutine-missing-hint-and-error.1103197/#post-7100494

"When in doubt, print it out!(tm)" - Kurt Dekker (and many others)

Note: the

print()

function is an alias for Debug.Log() provided by the MonoBehaviour class.

BEYOND that... if you have more information:

How to report your problem productively in the Unity3D forums:

http://plbm.com/?p=220

This is the bare minimum of information to report:

- what you want
- what you tried
- what you expected to happen
- what actually happened, log output, variable values, and especially any errors you see
- links to documentation you used to cross-check your work (CRITICAL!!!)

The purpose of YOU providing links is to make our job easier, while simultaneously showing us that you actually put effort into the process. If you haven't put effort into finding the documentation, why should we bother putting effort into replying?

 

This is the video I just recorded, I'm sure it's a Unity bug.

 

When you destroy something, it happens at the end of frame, not immediately. So what you're doing is marking three objects to be destroyed, and making three more, and thus have 6 buttons until the first three are cleaned up at the end of frame.

Your code has hard coded

GetChild(2);

which will be the third button that's been marked for destruction.

Generally you should not use the transform heirarchy for this sort of stuff. Manage your own list of buttons. When you instantiate them, add them to the list. When you destroy them, remove them from the list.

So no bug, just a subtle behaviour of Unity.

 

Subtle but fully documented.

https://docs.unity3d.com/ScriptReference/Object.Destroy.html

I quote:

"The object obj is destroyed immediately after the current Update loop..."

Definitely not immediately.

 

Thanks for the replies, I see.

 

Thank you very much for your help, this issue has been solved, thank you again, with your help I was able to solve this problem.

 

Thank you very much for your help, this issue has been solved, thank you again, with your help I was able to solve this problem.