主页 hero 以 SVG 动画展示从 async 函数、任务调度、TaskGroup、Actor 到 AsyncSequence 的全流程，让架构设计与中文本地化同频。 The hero SVG animates the complete flow—from async functions and the cooperative task scheduler to TaskGroup, actors, and AsyncSequence—aligning architecture and bilingual narration.
“异步数字化” 将 Swift 最新 async 机制拆成可执行模块：左侧 hero 是调度路径，右侧卡片呈现代码约定，全面覆盖 async/await、Task、TaskGroup、Actor、AsyncSequence 以及取消逻辑。 “Async Digitization” decomposes Swift’s latest concurrency primitives into executable modules: the hero visualises scheduling paths while the cards capture code-level conventions across async/await, Task, TaskGroup, actors, AsyncSequence, and cancellation.
异步函数默认运行在结构化上下文中，await 只在安全点让出线程；Swift 编译器会在捕获生命周期时进行逃逸检查。 Async functions execute inside structured contexts, yielding only at safe suspension points while the compiler enforces lifetime guarantees.
func fetchArticles() async throws -> [Article] {
async let summary = fetchSummary()
let pages = try await fetchPages()
return try await [summary] + pages
}TaskGroup Fan-out fan-in 让 IO 并发仍保持结构化；取消信号会沿父任务向下游传播。 TaskGroup fan-out/fan-in keeps IO concurrency structured while cancellation percolates down the parent chain.
try await withThrowingTaskGroup(of: Report.self) { group in
for source in sources {
group.addTask { try await ingest(source) }
}
return try await group.reduce(into: []) { $0.append($1) }
}Actor 用串行执行器包裹可变状态；@MainActor 确保 UI 更新在主线程。 Actors wrap mutable state with a serial executor, while @MainActor guarantees UI mutations on the main thread.
actor TimelineStore {
private var entries: [TimelineEntry] = []
func append(_ entry: TimelineEntry) {
entries.append(entry)
}
}AsyncSequence 以 backpressure 控制速率，AsyncStream 在闭包中生成值并自动完成或取消。 AsyncSequence imposes backpressure, and AsyncStream yields values inside a closure until completion or cancellation.
let stream = AsyncStream<Event> { continuation in
eventSource.onValue { continuation.yield($0) }
eventSource.onComplete { continuation.finish() }
}1. async 入口 1. async entry
swiftc 会把函数包装到异步上下文，插入可挂起点表 (suspend points)。 swiftc wraps the function into an async context and records its suspend points.
2. 任务调度 2. Task scheduling
Task 优先级 + cooperative executors 负责把工作单元映射到线程池。 Task priorities plus cooperative executors map work units onto the thread pool.
3. TaskGroup 拆分 3. TaskGroup fan-out
withTaskGroup 创建结构化子任务，完成后再 fan-in，以确保取消/错误一致性。 withTaskGroup spins structured children and fans in once they finish for consistent cancellation and error surfaces.
4. Actor 隔离 4. Actor isolation
@MainActor / 自定义 actor 执行器串行处理状态，避免 data race。 @MainActor or custom actors serialize access to mutable state to ward off data races.
5. AsyncSequence 消费 5. AsyncSequence consumption
for try await 循环按 backpressure（demand）拉取元素，适合流式 UI / I/O。 for try await loops apply demand-driven pulling, ideal for streaming UI or IO.
6. 取消与恢复 6. Cancellation & resume
Task.checkCancellation() / withTaskCancellationHandler 在每个挂起点收尾，resume 返回结果或抛错。 Task.checkCancellation() and withTaskCancellationHandler clean up at each suspension before resuming or throwing.