ViewController.swift

//  ViewController.swift

import UIKit
import Alamofire

class ViewController: UIViewController {
  
  override func viewDidLoad() {
    super.viewDidLoad()
    
    let d = Downloader(path: "/tmp/qiitags")
    d.download(1, endpoint: 100)
  }
}

struct Downloader {
  var path: String
  
  init(path: String){
    self.path = path
  }
  
  func download(start: Int, endpoint: Int) -> Void {
    if start > endpoint {
      return
    }
    
    let p = String(start)
    Alamofire
      .request(.GET, "https://qiita.com/api/v2/tags", parameters: ["page": p])
      .response { (request, response, data, error) in
        assert(error == nil)
        let json = NSString(data: data as NSData, encoding: NSUTF8StringEncoding)
        let path = "\(self.path)/\(p).json"
        let ret = json?.writeToFile(path, atomically: true, encoding: NSUTF8StringEncoding, error: nil) as Bool!
        assert(ret)
        NSThread.sleepForTimeInterval(1)
        self.download(start+1, endpoint: endpoint)
    }
  }
}