Swift并发：为什么不在其他后台线程上执行任务

我正在努力学习快速并发，但它带来了很多困惑.据我所知，任务{}是一个异步单元，它将允许我们从同步上下文中桥接异步函数调用.它类似于DispatchQueue.Global()，后者将在某个任意线程上执行该块.

override func viewDidLoad() {
        super.viewDidLoad()
        
        Task {
            do {
                    
                 let data = try await asychronousApiCall()
                 print(data)
                    
                } catch {
                    print("Request failed with error: \(error)")
                }
        }
        
        for i in 1...30000 {
            print("Thread \(Thread.current)")
        }
    }

下面是我的AsychronousApiCall函数

func asychronousApiCall() async throws -> Data {
        print("starting with asychronousApiCall")
        print("Thread \(Thread.current)")
        let url = URL(string: "https://www.stackoverflow.com")!
        // Use the async variant of URLSession to fetch data
        // Code might suspend here
        let (data, _) = try await URLSession.shared.data(from: url)
        
        return data
    }

当我try 这个实现时.我总是看到，在for loop完成之后，打印出"Start with asychronousApiCall"，线程是MainThread.

就像这样

Thread <_NSMainThread: 0x600000f10500>{number = 1, name = main}