Async Request Sample

ParallelDispatchQueue.swift

typealias AsyncCallback = () -> Void

func getFriends() {
    let dispatchGroup = DispatchGroup()
    let dispatchQueue = DispatchQueue(label: "twitterAPIQueue", attributes: .concurrent)
    
    // 非同期のGroupとQueueに書くメソッドを割り当てる
    dispatch(group: dispatchGroup, queue: dispatchQueue, method: getFollows)
    dispatch(group: dispatchGroup, queue: dispatchQueue, method: getFollowers)
    
    dispatchGroup.notify(queue: .main) {
        print("All Process Done!")
        
        // TODO: 突合する処理とかを書く
    }
}

private func dispatch(group: DispatchGroup, queue: DispatchQueue, method: @escaping (@escaping AsyncCallback) -> Void) {
    // ここで非同期のグループに入る
    group.enter()
    queue.async(group: group) {
    
        // 非同期で引数で与えられたメソッドを実行 
        method {
            // そのコールバックでgroupから抜ける
            group.leave()
        }
    }
}
/
private func getFollows(completion: @escaping AsyncCallback) {
    fetchFollowsAsync() {
        // Store follows
    
        completion()
    }
}

private func getFollowers(completion: @escaping AsyncCallback) {
    fetchFollowersAsync() {
        // Store 
    
        completion()
    }
}