```

add properties to AppDelegate

```
let dropboxStateChangedNotification = "dropboxStateChangedNotification"
let dropboxStateNotificationKey = "dropboxStateNotificationKey"
let dropbox = TinyDropbox.shared```

add AppDelegate as dropbox delegate

``` class AppDelegate: UIResponder, UIApplicationDelegate, TinyDropboxDelegate {```

```
func application(_ application: UIApplication, didFinishLaunchingWithOptions launchOptions: [UIApplicationLaunchOptionsKey: Any]?) -> Bool {
    dropbox.delegate = self
    // Override point for customization after application launch.
    return true
}```

```
// MARK: TinyDropboxDelegate

func dropbox(_ dropbox: TinyDropbox, didChangeStateTo state: TinyDropboxState) {
    let userInfo = [dropboxStateNotificationKey: state]
    NotificationCenter.default.post(name: NSNotification.Name(rawValue: dropboxStateChangedNotification), object: self, userInfo: userInfo)
}

func dropbox(_ dropbox: TinyDropbox, didReceiveIncomingChanges changes: Array<DropChange>) {

}
```

```
func application(_ app: UIApplication, open url: URL, options: [UIApplicationOpenURLOptionsKey : Any] = [:]) -> Bool {
    let result = dropbox.handleAuthorisationRedirectURL(url)
    return result
}
```

```
 private func subscribeToNotifications () {
    let appDelegate = UIApplication.shared.delegate as! AppDelegate
    NotificationCenter.default.addObserver(self,
                                           selector: #selector(ListDropboxViewController.dropboxDidCahngeState(notification:)),
                                           name: NSNotification.Name(rawValue: appDelegate.dropboxStateChangedNotification),
                                           object: appDelegate)
}

func dropboxDidCahngeState (notification: NSNotification) {
    let appDelegate = UIApplication.shared.delegate as! AppDelegate
    let state = notification.userInfo?[appDelegate.dropboxStateNotificationKey];
    
    if let state = state as? TinyDropboxState{
        if state == .connected
        || state == .reconnected {
            download(using: appDelegate.dropbox)
       }
    }
}```

```
private func download(using dropbox: TinyDropbox) {
dropbox.append(path: "/books")
    dropbox.listDirectory { (list: DropboxFilesList, error :DropboxError?) in
        guard list != nil, list!.count > 1 else {
            return
        }
        
        var path = NSSearchPathForDirectoriesInDomains(.documentDirectory, .userDomainMask, true)[0];
        path.append("/book.pdf")
        let url = URL.init(fileURLWithPath: path)
        let richable = try? url.checkResourceIsReachable()
        
        guard richable == nil || richable == false else {
            self.open(fileAt: url)
            return
        }
        
        print(url);
        
        dropbox.download(atPath: list![0], to: url, completion: { [weak self]  (error: DropboxError?) in
            if let error = error {
                print(error)
            } else {
                self?.open(fileAt: url)
            }
        })
    }
}```