Working with web APIs in Swift Leah Culver Twilio Signal 2015 

Dropbox Developer Platform 

New! Dropbox API v2 

API v2 preview • HTTP POST method • JSON in the request and response body • fewer HTTP status codes • more descriptive error messages • general cleanup ✨ 

API v2 preview endpoints User endpoints users/get_account users/get_current_account File endpoints files/get_metadata files/list_folder files/upload files/download files/search … and more! 

New! SwiftyDropbox 

SwiftyDropbox SDK (v0.1) methods User endpoints usersGetAccount usersGetCurrentAccount File endpoints filesGetMetadata filesListFolder filesUpload filesDownload filesSearch … and more! 

+ + + … 

+ + + ⌚ 

= 

Photo Watch Photos from your Dropbox on your Apple Watch 

(phone simulator) 

github.com/dropbox/SwiftyDropbox blogs.dropbox.com/developers import SwiftyDropbox 

Link account with Dropbox func application(application: UIApplication, didFinishLaunchingWithOptions launchOptions: [NSObject: AnyObject]?) -> Bool { DropboxAuthManager.sharedAuthManager = DropboxAuthManager(appKey: “APP_KEY”) return true } AppDelegate.swift 

@IBAction func linkButtonPressed(sender: AnyObject) { // Present view to log in DropboxAuthManager.sharedAuthManager.authorizeFromController(self) } ViewController.swift 

OAuth 2 on iOS • switch to Safari for log in and authorization 

OAuth 2 on iOS • switch to Safari for log in and authorization 

OAuth 2 on iOS • switch to Safari for log in and authorization • present web view controller 

OAuth 2 on iOS • switch to Safari for log in and authorization • present web view controller 

OAuth 2 on iOS • switch to Safari for log in and authorization • present web view controller • switch to Dropbox app (“DAuth”, not yet implemented) 

func application(application: UIApplication, openURL url: NSURL, sourceApplication: String?, annotation: AnyObject?) -> Bool { if let authResult = DropboxAuthManager.sharedAuthManager.handleRedirectURL(url) { switch authResult { case .Success(let token): println("Success! User is logged into Dropbox.") case .Error(let error, let description): println("Error: \(description)") } } return false } AppDelegate.swift 

Set up DropboxClient // Check if the user is logged in if let token = DropboxAuthManager.sharedAuthManager.getFirstAccessToken() { // Set the sharedClient for re-use DropboxClient.sharedClient = DropboxClient(accessToken: token) … } ViewController.swift 

List user’s Dropbox files self.filenames = [] // List contents of app folder DropboxClient.sharedClient.filesListFolder(path: "").response { response, error in if let result = response { for entry in result.entries { // Check that file is a photo (by file extension) if fileURL.absoluteString!.hasSuffix(".jpg") || fileURL.absoluteString!.hasSuffix(".png") { // Add photo self.filenames?.append(entry.name) } } } } ViewController.swift 

UIPageViewControllerDataSource func presentationCountForPageViewController(pageViewController: UIPageViewController) -> Int // Number of pages is number of photos return self.filenames!.count } 

UIPageViewControllerDataSource func pageViewController(pageViewController: UIPageViewController, viewControllerAfterViewController viewController: UIViewController) -> UIViewController? { var nextIndex = … let photoViewController = self.storyboard?.instantiateViewControllerWithIdentifier("PhotoViewController") as! PhotoViewController photoViewController.filename = self.filenames![nextIndex] return photoViewController } 

Download photo class PhotoViewController: UIViewController { @IBOutlet weak var imageView: UIImageView! var filename: String? override func viewDidLoad() { … // Download the photo from Dropbox // A thumbnail would be better but there's no endpoint for that in API v2 yet! DropboxClient.sharedClient.filesDownload(path: “/\(self.filename)").response { response, error in if let (metadata, data) = response, image = UIImage(data: data) { // Resize image for watch (so it's not huge) let resizedImage = self.resizeImage(image) // Display image self.imageView.image = resizedImage } } } } 

Cache files… share with watch…
 app group! 

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Store photos in app group // Get app group shared by phone and watch let containerURL = NSFileManager.defaultManager() .containerURLForSecurityApplicationGroupIdentifier("group.com.Dropbox.DropboxPhotoWatch") if let fileURL = containerURL?.URLByAppendingPathComponent(filename) { if let data = NSData(contentsOfURL: fileURL) { // Display image self.imageView.image = UIImage(data: data) } else { // Download the photo from Dropbox, resize, then display … self.imageView.image = resizedImage // Save image to local filesystem app group - allows us to access in the watch let resizedImageData = UIImageJPEGRepresentation(resizedImage, 1.0) resizedImageData.writeToURL(fileURL, atomically: true) } } 

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InterfaceController.swift override func awakeWithContext(context: AnyObject?) { super.awakeWithContext(context) // Get images from the shared app group if let images = self.getImagesFromAppGroup() { // Data for each photo view let controllerNames = [String](count: images.count, repeatedValue: "PhotoInterfaceController") let contexts = images.map({ image in ["image": image] }) // Update watch display WKInterfaceController.reloadRootControllersWithNames(controllerNames, contexts: contexts) } } 

InterfaceController.swift private func getImagesFromAppGroup() -> Array? { var images = [UIImage]() // Get app group shared by phone and watch if let containerURL = NSFileManager.defaultManager() .containerURLForSecurityApplicationGroupIdentifier("group.com.Dropbox.DropboxPhotoWatch") { // Fetch all files in the app group for fileURL in NSFileManager.defaultManager().contentsOfDirectoryAtURL(…) as! Array { // Check that file is a photo (by file extension) if fileURL.absoluteString!.hasSuffix(".jpg") || fileURL.absoluteString!.hasSuffix(".png") { // Add image to array of images if let data = NSData(contentsOfURL: fileURL), image = UIImage(data: data) { images.append(image) } } } return images } 

PhotoInterfaceController.swift class PhotoInterfaceController: WKInterfaceController { @IBOutlet weak var image: WKInterfaceImage! override func awakeWithContext(context: AnyObject?) { super.awakeWithContext(context) if let data = context as? Dictionary { self.image.setImage(data["image"]) } } } 

(watch simulator) 

github.com/dropbox/PhotoWatch Photo Watch 

Working with APIs in Swift 

let maxSize: CGFloat = 200.0 var size: CGSize? Constants and Variables 

Optionals if let (metadata, data) = response { // … } else { println("Error: \(error!)") } 

Optional chaining (new!) if let (metadata, data) = response, image = UIImage(data: data) { // Display image self.imageView.image = image } else { println("Error downloading file from Dropbox: \(error!)") } 

Emoji! let = DropboxClient.sharedClient 

HTTP requests Recommended library: NSURLSession Check out: Alamofire 

JSON Recommended library: NSJSONSerialization Check out: ?? 

Singleton for a default - shared instance 

iOS app longer lifetime of in-memory code Web app request/response pattern API clients DropboxClient DropboxAuthManager 

+ (id)sharedManager { static MyManager *sharedManager = nil; static dispatch_once_t onceToken; dispatch_once(&onceToken, ^{ sharedManager = [[self alloc] init]; }); return sharedManager; } class MyManager { static let sharedManager = MyManager() init() { //... } } Singletons Obj-C Swift 

Enumerations if let authResult = DropboxAuthManager.sharedAuthManager.handleRedirectURL(url) { switch authResult { case .Success(let token): println("Success! User is logged into Dropbox.") case .Error(let error, let description): println("Error: \(description)") } } 

public enum DropboxAuthResult { case Success(DropboxAccessToken) case Error(OAuth2Error, String) } public func handleRedirectURL(url: NSURL) -> DropboxAuthResult? { … } Enumerations 

DropboxClient.sharedClient.filesListFolder(path: "").response { response, error in if response != nil { println(response) } else if error != nil { println("Error: \(error)") } } Completion handler 

Feedback? [email protected] Session feedback? Text @T14 to 39242 

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