README: Improved build and usage instructions.

README.md

@@ -1,5 +1,9 @@
 # Godot iOS plugins
 
+> [!NOTE]
+>
+> iOS plugins are not editor plugins.
+
 [`master` branch](https://github.com/godotengine/godot-ios-plugins/tree/master) is the current development branch and can introduce breaking changes to plugin's public interface.
 [`3.3` branch](https://github.com/godotengine/godot-ios-plugins/tree/3.3)'s aim is to provide same public interface as it was before the switch to new iOS plugin system.
 
@@ -44,12 +48,20 @@ scons platform=iphone target=debug
 
 ### For Godot 4.x:
 
-```bash
-scons platform=ios target=debug
-```
 
-You don't have to wait for full engine compilation, as header files are generated first.
-Once the actual compilation starts, you can stop this command by pressing <kbd>Ctrl + C</kbd>.
+1. After cloning this repository, go to `godot` submodule and switch to the tag of the engine version you are working with. For example, `git checkout 4.4-stable`.
+
+2. If the version is lower than 4.4, you will need to cherry-pick the commit from [here](https://github.com/godotengine/godot/pull/97510 ).  Depending on the version, it might cause a conflict in the file `drivers/vulkan/rendering_context_driver_vulkan.h` which you resolve by taking the changes from the cherry-picked commit for the conflicting section only.
+
+3. Install `scons` if it is not already installed (eg `brew install scons`).
+
+4. [Build Godot for iOS target](https://docs.godotengine.org/en/stable/contributing/development/compiling/compiling_for_ios.html): `scons platform=ios target=editor`
+
+
+5. Run the plugin creation script. This step needs to be repeated for each of the plugins you want to use. Go to the root of this repository then run `./scripts/generate_xcframework.sh <plugin_name> <debug|release|release_debug> 4.0`. The result will be an xcframework in bin directory.
+
+
+### Extra info
 
 - Run the command below to generate an `.a` static library for chosen target:
 
@@ -59,19 +71,36 @@ scons target=<debug|release|release_debug> arch=<arch> simulator=<no|yes> plugin
 
 **Note:** Godot's official `debug` export templates are compiled with the `release_debug` target, *not* the `debug` target.
 
-## Building a `.a` library
+#### Building a `.a` library
 
 - Run `./scripts/generate_static_library.sh <plugin_name> <debug|release|release_debug> <godot_version>`
   to generate `fat` static library with specific configuration.
 - The result `.a` binary will be stored in the `bin/` folder.
 
-## Building a `.xcframework` library
+#### Building a `.xcframework` library
 
 - Run `./scripts/generate_xcframework.sh <plugin_name> <debug|release|release_debug> <godot_version>`
   to generate `xcframework` with specific configuration.
   `xcframework` allows plugin to support both `arm64` device and `arm64` simulator.
 - The result `.xcframework` will be stored in the `bin/` folder as well as intermidiate `.a` binaries.
 
+
+## Adding plugins to a Godot project
+
+More detailed instructions can be found in the [official docs](https://docs.godotengine.org/en/stable/tutorials/platform/ios/ios_plugin.html#loading-and-using-an-existing-plugin).
+
+1. Build both release and debug xcframeworks of the desired plugin.
+
+2. In your Godot project, create `res://ios/plugin` and copy there the `<plugin name>.gdip` (from the plugin source directory in this repository) and both `*.xcframework` files for the plugin (from the `bin/` directory).
+
+3. Go to **Project > Export** and select the iOS export preset (or create one if it doesn't exist already). In the **Options** tab, scroll to **Plugins** and enable the plugin.
+
+## C\#
+
+It is possible to verify that the plugin's singleton is loaded using `Engine.HasSingleton("InAppStore")` and get access to it with `Engine.GetSingleton("InAppStore")`.
+
+The return type is always `GodotObject`. The methods which the plugin expose can be called indirectly with `Variant Call(StringName method, params Variant[] @args)` metod of `GodotObject`.
+
 ## Documentation
 
 Each plugin provides a `README.md` file which contains documentation and examples.