如何打破内部使用异步DispatchQueue的循环

let dispatchGroup = DispatchGroup()

for item in items {
    dispatchGroup.enter()
    
    DispatchQueue.global().async {
        // 异步任务代码
        
        dispatchGroup.leave()
    }
}

dispatchGroup.notify(queue: .main) {
    // 所有任务完成后的代码
}

func performAsyncTask(index: Int, completion: @escaping () -> Void) {
    if index >= items.count {
        completion()
        return
    }
    
    DispatchQueue.global().async {
        // 异步任务代码
        
        performAsyncTask(index: index + 1, completion: completion)
    }
}

performAsyncTask(index: 0) {
    // 所有任务完成后的代码
}

let semaphore = DispatchSemaphore(value: 1)
var currentIndex = 0

func performAsyncTask(completion: @escaping () -> Void) {
    DispatchQueue.global().async {
        semaphore.wait()
        
        if currentIndex >= items.count {
            semaphore.signal()
            completion()
            return
        }
        
        let currentItem = items[currentIndex]
        currentIndex += 1
        
        // 异步任务代码
        
        semaphore.signal()
        
        performAsyncTask(completion: completion)
    }
}

performAsyncTask {
    // 所有任务完成后的代码
}