Demo of the Network Starter Kit

This is the script for Tuesday's Columbia iOS meetup.

GET Request

Problem statement.

Just to get this output: label:: Agar.io

we have all this code:

let url = NSURL(string: "https://itunes.apple.com/us/rss/topfreeapplications/limit=10/json")
let request = NSMutableURLRequest(URL: url!)
let session = NSURLSession.sharedSession()
let task = session.dataTaskWithRequest(request){
    (data, response, error) -> Void in
    println("data:: \(data)")
    println("response:: \(response)")
    println("error:: \(error)")
    
    // data: is still totally unreadable, and needs to be converted to JSON

    var jsonError: NSError?
    if let json = NSJSONSerialization.JSONObjectWithData(data, options: nil, error: &jsonError) as? [String: AnyObject] {
        
        println("json:: \(json)")
        
        if let feed = json["feed"] as? NSDictionary {
            if let entry = feed["entry"] as? NSArray {
                if let appObject = entry[0] as? NSDictionary {
                    if let imName = appObject["im:name"] as? NSDictionary {
                        if let label = imName["label"] as? String {
                            println("label:: \(label)")
                        }
                    }
                }
            }
        }
    }

}
task.resume()

Pain points:

Lots of boilerplate just to setup a network request. Imagine if you have a dozen API endpoints.
NSJSONSerialization is kind of yucky. We still need to protect against jsonError bombing.
Check out the if-let pyramid of doom

GET using AlamoFire and SwiftyJSON

Syntax is tighter and easier to read.

let url = "https://itunes.apple.com/us/rss/topfreeapplications/limit=10/json"
request(.GET, url)
    .responseJSON { (_, _, data, _) in
        let json = JSON(data!)
        let label = json["feed"]["entry"][0]["im:name"]["label"].stringValue
        println("label:: \(label)")
    }

What about POST?

This is what a vanilla POST looks like. Not only do you need to convert your dictionary to JSON, you also need to set application/json headers.

let url = NSURL(string: "http://httpbin.org/post")
let params = [ "foo" : "bar" ]
var err: NSError?

let request = NSMutableURLRequest(URL: url!)
request.HTTPMethod = "POST"
request.HTTPBody = NSJSONSerialization.dataWithJSONObject(params, options: nil, error: &err)
request.addValue("application/json", forHTTPHeaderField: "Content-Type")
request.addValue("application/json", forHTTPHeaderField: "Accept")

let session = NSURLSession.sharedSession()
let task = session.dataTaskWithRequest(request) { data, response, error -> Void in
    println("data:: \(data)")
    println("response:: \(response)")
    println("error:: \(error)")
    
    var jsonError: NSError?
    if let json = NSJSONSerialization.JSONObjectWithData(data, options: nil, error: &jsonError) as? [String: AnyObject] {
        
        println("json:: \(json)")
    }
    
}
task.resume()

A better way to POST

This does the same thing.

let params = [ "foo" : "bar" ]
request(.POST, "http://httpbin.org/post", parameters: params, encoding: .JSON)
    .responseJSON { (_, _, data, _) in
        println("data:: \(data)")
    }

How about downloading images

This is the normal way:

let url = NSURL(string: "http://tsumtsumdisney.com/wp-content/uploads/2014/10/Snow-White-and-the-Seven-Dwarfs-Tsum-Tsum-Set-of-8-0-0.jpg")
let request = NSURLRequest(URL: url!)
let mainQueue = NSOperationQueue.mainQueue()
NSURLConnection.sendAsynchronousRequest(request, queue: mainQueue) {
    (response, data, error) -> Void in
    if error == nil {
        let image = UIImage(data: data)
        dispatch_async(dispatch_get_main_queue()) {
            self.imageView.image = image
        }
    }
}

A better way to download images

request(.GET, "http://tsumtsumdisney.com/wp-content/uploads/2014/10/Snow-White-and-the-Seven-Dwarfs-Tsum-Tsum-Set-of-8-0-0.jpg")
    .responseImage() { (request, _, image, error) in
        if error == nil && image != nil {
            self.imageView.image = image
        }
    }

chenr2/demoNetwork.md