Kotlin Multiplatform Academy · 课时

跨平台 ViewModel 基类

保存两个平台都能使用的状态和作用域

第 1 / 4 课13 个步骤

跨平台 ViewModel 基类 是 CoddyKit 上的免费 Kotlin Multiplatform Academy 课时。这是第 1 节课，共 4 节。你可以在下方免费阅读本课时的完整内容 — 然后在浏览器中使用内置代码编辑器和全天候 AI 导师进行实践。这是 Kotlin Multiplatform Academy 学习路径的一部分，你的进度在网页和 CoddyKit 应用中同步。 Kotlin Multiplatform Academy 课程共包含 4 节课。

本课时的部分内容尚未翻译，以英文显示。

Why Share the ViewModel?

A ViewModel holds screen state and logic. In KMP you write it once in shared code so both apps stay perfectly in sync. 🎉

Logic, Not Pixels

Your shared ViewModel decides what the screen shows. The native UI decides how to draw it. That split is the heart of KMP.

A Plain Class to Start

At its core a ViewModel is just a normal Kotlin class living in commonMain. No magic, no framework required to begin.

class CounterViewModel {
    var count = 0
}

It Needs a Scope

Async work needs a CoroutineScope. Every ViewModel keeps one so it can launch coroutines and cancel them later cleanly.

val scope = CoroutineScope(
    SupervisorJob() + Dispatchers.Main
)

SupervisorJob Keeps Siblings Alive

Using a SupervisorJob means one failing coroutine will not cancel the others in the same scope. Failures stay isolated.

A Reusable Base Class

Put the shared scope in an open base class so every screen's ViewModel inherits the same lifecycle plumbing for free.

open class BaseViewModel {
    protected val scope =
        CoroutineScope(SupervisorJob() + Dispatchers.Main)
}

Always Provide Cleanup

Add a clear() method that cancels the scope. When the screen goes away, the platform calls it so no work leaks.

open fun clear() {
    scope.cancel()
}

Extend the Base

Now a real screen just extends the base. It gets a ready scope and clean shutdown without repeating the boilerplate.

class HomeViewModel : BaseViewModel() {
    // screen logic here
}

androidx Has Its Own ViewModel

KMP now ships a multiplatform androidx.lifecycle.ViewModel. It gives you a managed viewModelScope on every target.

viewModelScope for Free

Extend that ViewModel and you get a built-in viewModelScope that is cancelled automatically when the ViewModel clears.

class HomeViewModel : ViewModel() {
    fun load() = viewModelScope.launch { }
}

One Class, Both Platforms

Whichever base you pick, the same shared ViewModel drives Android and iOS. Write the behavior once, trust it everywhere.

Quick Check

Let's lock in why a ViewModel carries a scope.

在交互式课程中回答

Recap

A shared ViewModel is a plain Kotlin class with a CoroutineScope and a clear() to cancel it. Build once, reuse on both apps. 🚀

免费开始

用 AI 导师学习 Kotlin — 免费

在浏览器中编写并运行真实代码，获得全天候 AI 导师的即时帮助，并在网页或应用中继续学习。

课程: 30
课程: 120

免费开始学习查看完整课程

常见问题解答

「跨平台 ViewModel 基类」课时是免费的吗？

是的 — 「跨平台 ViewModel 基类」的完整文本可在网页上免费阅读。要进行交互式练习（内置代码编辑器和全天候 AI 导师）并解锁 Kotlin Multiplatform Academy 课程的其余内容，请升级到 CoddyKit PRO。 Kotlin Multiplatform Academy 课程共包含 4 节课。

「跨平台 ViewModel 基类」这节课中我会学到什么？

保存两个平台都能使用的状态和作用域你通过在浏览器中直接运行的动手代码来练习 Kotlin Multiplatform Academy，全天候 AI 导师会在你学习这节课的过程中回答你的问题。

学习 Kotlin Multiplatform Academy 需要有经验吗？

无需任何先前经验。CoddyKit 上的 Kotlin Multiplatform Academy 课程适合初学者到高级学习者，你可以从这里开始或从头开始，按照自己的节奏学习。这是第 1 节课，共 4 节。

「跨平台 ViewModel 基类」课时需要多长时间？

大多数 CoddyKit 课程大约需要 5–10 分钟。每节课都很精短且互动，所以你能稳步进步，并在网页和应用中从离开的地方继续。

我能在这节 Kotlin Multiplatform Academy 课中编写并运行代码吗？

能。每节 Kotlin Multiplatform Academy 课都包含内置代码编辑器，你可以在浏览器中直接编写并运行真实代码，并获得即时 AI 反馈 — 无需本地设置。

此课程中的所有课时

← 返回 Kotlin Multiplatform Academy