Unity editor scripting (part 3) - your own build (Android) tool

One of things I had scripted very early working as Unity developer, was building.

When doing a build "normally", you have to click through menu (File/Build Settings, or Ctrl+Shift+B), then choose name for the file (or use the old one, and accept the dialog asking whether to overwrite it), blah blah blah... 

But editor scripting allows us to avoid this pain: we can create a script, called from our custom menu (or via custom keyboard shortcut, like Ctrl+Shit+K, which I guess doesn't do anything interesting normally), which simply creates .aab or .apk file with, say, current date and time in name. No choosing name, no clicking through menus.

How to achieve such awesome result? Start with creating file Build.cs in your Assets/Editor folder and paste the following code there (should work for Unity 2020.3.10 and similar):

What's going on there? The GetEnabledScenes()  method simply returns all the enabled scenes in the current configuration. The build itself is taking place in PerformBuild() method. First (line 20) we get the scenes to be enabled in build. Then we get out desktop folder path (21). Then we create a string containing current time and date, so that every build could be easily identified and no two would overwrite (23), and then construct our file name with extension (24).

Then we create a BuildPlayerOptions object, containing all this information and specifying the target as Android.  And then, using EditorUserBuildSettings , we set up build features: enable Proguard, set the build to bundle (.aab, not .apk), and mark the build as release. Finally, the BuildPipeline.BuildPlayer(bpo);  runs the build itself.

In case you want .apk for debug, simply change the extension in line 26 to from .aab to .apk, then buildAppBundle in line 35 to false instead of true, and then  build type to AndroidBuildType.Release;  to AndroidBuildType.Debug in line 36.

Now having that scripted you can build your game using custom menu (without needing to specify file name everytime), or using keyboard schortcut Ctrl+Shift+K. But you can do one more thing - you can build your app without opening Unity. You can simply write a bash (Mac) or batch (Windows .bat) script to build the app for you, and then run it. It's helpful, if you build on different machine than you develop on.

For Windows, create a build.bat file with contents as follows (of course set appropriate the path to your Unity installation) and place it in parent folder of your project folder (not next to Assets, but next to folder containing Assets... I'll add a graph below ;D

Folder structure (it's really important)

So now when you run that script, it should build a nice .aab file on your Desktop :) If you want to use it that way (from the script, not via shortcut or menu), you should exit Unity before running it.

If you use Unity 2019 (not 2020), the script from the first listing may not work. But the problem is very simple: in Unity 2019.x you simply have to change the line 34 (the way minification is enabled has changed in the meantime):

Generally, if something does not work, doublecheck and triplecheck your file names and method names in both Unity and .bat scripts, also class and namespace and files placement. This whole system seems to be quite picky about it.

Side note: I've just realized a problem with using gists on blogger: you can't see the code in WYSIWYG mode... On the other hand, it's easier to write about code with line numbers ;) ... I'll have to think about it.