SwiftUI中的`Task`和`async`有什么区别

Question

So I have seen code like:

func doSomething() {
  async {
    let foo = await something()
  }
}

vs

func doSomething() {
  Task {
    await doSomething()
  }
}

There's also a modifier version of the Task:

TextView(...)
  .task {
    let foo = await something()
  }

I am wondering what's the difference between these and which one should I use?

Answer 1

async {... } is deprecated. I can't even find the documentation page for the async function. It has been replaced by Task {... } , which uses this initialiser of Task .

Task {... } runs an asynchronous operation as a top level task.

The .task view modifier , on the other hand, is a view modifier , and runs the asynchronous operation when the view appears . Importantly, this task has the same life time as the view. If the view gets removed, the task gets cancelled too.

Compare:

func foo() {
    Task {
        await doWork() // gets started when foo is called
    }
}

and

Text("Hello")
    .task {
        // gets started when "Hello" appears,
        // *not* when .task is called
        await doWork() 
    }