加载与错误状态
显示加载指示器并优雅地处理失败。
加载与错误状态 是 CoddyKit 上的免费 SwiftUI Academy 课时。 这是第 4 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 SwiftUI Academy 学习路径的一部分，你的进度在网页和 CoddyKit 应用中同步。 SwiftUI 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。
Every Fetch Has Phases
A real request moves through states: loading, success, and failure. Showing each one makes your app feel trustworthy. 🔄
Modeling State with an Enum
An enum captures each phase cleanly. The view then switches on it to decide exactly what to display.
enum Phase { case loading, loaded([User]), failed(String) }Showing a Spinner
While loading, show a ProgressView. This native spinner reassures users that something is happening behind the scenes.
ProgressView("Loading...")Switching on the Phase
Use a switch in your body to render a spinner, the data, or an error view based on the current phase.
switch phase {
case .loading: ProgressView()
case .failed(let msg): Text(msg)
case .loaded(let users): List(users)
}Catching the Error
Wrap the fetch in do/catch and move to the failed phase on error, storing a friendly message for the screen.
catch { phase = .failed("Could not load") }Friendly Error Messages
Avoid raw error text. Show a clear sentence the user understands, like "Check your connection and try again."
Offering a Retry
On failure, add a retry button that runs the fetch again. Letting users recover beats a dead-end error screen.
Button("Retry") { Task { await load() } }The Empty State
Success with no data deserves its own empty view, like "No results yet", so the screen never looks broken.
Setting Loading First
Move to the loading phase before awaiting. That instantly shows the spinner so the screen never feels frozen.
phase = .loading
phase = .loaded(try await loadUsers())Avoiding Flicker
For very fast responses, a tiny delay before hiding the spinner prevents a jarring flash of loading UI.
Wiring It to .task
Kick off the whole flow from .task, which sets loading, fetches, and lands on loaded or failed automatically.
.task { await load() }Quick Check
Quick check on handling request phases.
Recap: States
You now model fetches as loading, loaded, and failed, show a spinner and friendly errors with retry, and drive it all from .task. 🎯
常见问题解答
「加载与错误状态」课时是免费的吗？
是的 — 「加载与错误状态」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 SwiftUI Academy 课程的其余内容，请升级到 CoddyKit PRO。 SwiftUI Academy 课程共包含 4 节课。
「加载与错误状态」这节课中我会学到什么？
显示加载指示器并优雅地处理失败。 你通过在浏览器中直接运行的动手代码来练习 SwiftUI 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 SwiftUI Academy 需要有经验吗？
无需任何先前经验。CoddyKit 上的 SwiftUI 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 4 节课，共 4 节。
「加载与错误状态」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 SwiftUI Academy 课中编写并运行代码吗？
能。每节 SwiftUI 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。