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Basic Table View app with JSON Client

Our first try livecoding with Swift

Here’s an hour-long livecoding video we did last week to make a basic table view app that downloads and parses JSON and builds a set of dynamic, expanding table view cells. Lots of helfup tips and tricks for working with Xcode and Swift are sprinkled throughout. The resulting code is available on Github.

Want to be notified when livecoding is coming up? Follow @nickoneill on Twitter.

Some relevant code snippits from the video so you can follow along:

This is our viewDidLoad override in our main view controller. Note the estimatedRowHeight so that we can automatically grow and shrink our table view cell sizes.

Our ColorClient (code below), fetches a list of colors and returns them to us as ColorBox objects.

override func viewDidLoad() {
    super.viewDidLoad()

    tableView.estimatedRowHeight = 125
    tableView.rowHeight = UITableViewAutomaticDimension

    ColorClient.sharedClient.getColors {[weak self](colors) in
        self?.colors = colors

        dispatch_async(dispatch_get_main_queue(), {
            self?.tableView.reloadData()

            if colors.count > 0 {
                self?.selected(colors.first!.color)
            }
        })
    }
}

The ColorBox object uses a failable initializer based on if we can correctly decode the correct data from the JSON file. Note the guard usage here!

struct ColorBox {
    let name: String
    let desc: String
    let color: UIColor

    init?(json: Dictionary<String, AnyObject>) {
        guard let name = json["name"] as? String else {
            return nil
        }
        self.name = name

        guard let colors = json["rgb"] as? [Int] where colors.count == 3 else {
            return nil
        }
        let color = UIColor(red: CGFloat(colors[0]) / 255, green: CGFloat(colors[1]) / 255, blue: CGFloat(colors[2]) / 255, alpha: 1)
        self.color = color

        if let desc = json["description"] as? String {
            self.desc = desc
        } else {
            self.desc = ""
        }
    }
}

Configuring our table cell display is simple and important. I always move this into a configure method on my custom table view cells.

class ColorBoxTableViewCell: UITableViewCell {
    @IBOutlet weak var colorView: UIView!
    @IBOutlet weak var titleLabel: UILabel!
    @IBOutlet weak var descLabel: UILabel!

    func configure(color: ColorBox) {
        titleLabel.text = color.name
        descLabel.text = color.desc

        colorView.backgroundColor = color.color
    }
}

The core of the app is a custom API client, based on the Swift API client we featured here previously.

class ColorClient {
    static let sharedClient = ColorClient()

    func getColors(completion: ([ColorBox]) -> ()) {
        get(clientURLRequest("videosrc/colors.json")) { (success, object) in
            var colors: [ColorBox] = []

            if let object = object as? Dictionary<String, AnyObject> {
                if let results = object["results"] as? [Dictionary<String, AnyObject>] {
                    for result in results {
                        if let color = ColorBox(json: result) {
                            colors.append(color)
                        }
                    }
                }
            }

            completion(colors)
        }
    }

    private func get(request: NSMutableURLRequest, completion: (success: Bool, object: AnyObject?) -> ()) {
        dataTask(request, method: "GET", completion: completion)
    }

    private func clientURLRequest(path: String, params: Dictionary<String, AnyObject>? = nil) -> NSMutableURLRequest {
        let request = NSMutableURLRequest(URL: NSURL(string: "https://thatthinginswift.com/"+path)!)

        return request
    }

    private func dataTask(request: NSMutableURLRequest, method: String, completion: (success: Bool, object: AnyObject?) -> ()) {
        request.HTTPMethod = method

        let session = NSURLSession(configuration: NSURLSessionConfiguration.defaultSessionConfiguration())

        session.dataTaskWithRequest(request) { (data, response, error) -> Void in
            if let data = data {
                let json = try? NSJSONSerialization.JSONObjectWithData(data, options: [])
                if let response = response as? NSHTTPURLResponse where 200...299 ~= response.statusCode {
                    completion(success: true, object: json)
                } else {
                    completion(success: false, object: json)
                }
            }
        }.resume()
    }
}


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