Scripting concepts
Although Unity uses an implementation of the standard Mono runtime for scripting, it still has its own practices and techniques for accessing the engine from scripts. This section explains how objects created in the Unity editor are controlled from scripts, and details the relationship between Unity’s gameplay features and the Mono runtime.
Creating and Using Scripts(场景中的游戏对象，GameObjects)
The behavior of GameObjects is controlled by the Components that are attached to them. Although Unity’s built-in Components can be very versatile, you will soon find you need to go beyond what they can provide to implement your own gameplay features. Unity allows you to create your own Components using scripts. These allow you to trigger game events, modify Component properties over time and respond to user input in any way you like.
A script makes its connection with the internal workings of Unity by implementing a class which derives from the built-in class called MonoBehaviour. You can think of a class as a kind of blueprint for creating a new Component type that can be attached to GameObjects. Each time you attach a script component to a GameObject, it creates a new instance of the object defined by the blueprint. The name of the class is taken from the name you supplied when the file was created. The class name and file name must be the same to enable the script component to be attached to a GameObject.
The main things to note, however, are the two functions defined inside the class. The Update function is the place to put code that will handle the frame update for the GameObject. This might include movement, triggering actions and responding to user input, basically anything that needs to be handled over time during gameplay. To enable the Update function to do its work, it is often useful to be able to set up variables, read preferences and make connections with other GameObjects before any game action takes place. The Start function will be called by Unity before gameplay begins (ie, before the Update function is called for the first time) and is an ideal place to do any initialization.
As noted above, a script only defines a blueprint for a Component and so none of its code will be activated until an instance of the script is attached to a GameObject. You can attach a script by dragging the script asset to a GameObject in the hierarchy panel or to the inspector of the GameObject that is currently selected. There is also a Scripts submenu on the Component menu which will contain all the scripts available in the project, including those you have created yourself.
Instantiating Prefabs at run time(类/蓝图，预制件Prefabs)
Prefabs come in very handy when you want to instantiate complicated GameObjects or collections of GameObjects at run time. Compared with creating GameObjects from scratch using code, instantiating Prefabs using code has many advantages because you can:
- Instantiate a Prefab using one line of code. Creating equivalent GameObjects from scratch requires many more lines of code.
- Set up, test, and modify the Prefab quickly and easily using the Scene view, Hierarchy and Inspector
- Change which Prefab is instantiated without changing the code. You can make a simple rocket into a super-charged rocket, without any code changes.
Source
接下来读
https://docs.unity3d.com/2020.3/Documentation/Manual/ExecutionOrder.html