The idea of this app is to give users information about cities such as the current weather, pictures, history, and cities that are around.

How can we do it? Firstly, we have to decide on how the app is going to suggest a city to the user. Of course, the most logical city would be the city where the user is located, which means that we have to use the Core Location framework to retrieve the device's coordinates with the help of GPS.

Once we have retrieved the user's location, we can search for cities next to it. To do this, we are going to use a service from http://www.geonames.org/.

Another piece of information that will be necessary is the weather. Of course, there are a lot of websites that can give us information on the weather forecast, but not all of them offer an API to use it for your app. In this case, we are going to use the Open Weather Map service.

What about pictures? For pictures, we can use the famous Flickr. Easy, isn't it? Now that we have the necessary information...

Before we start coding, we are going to register the needed services and create an empty app. First, let's create a user at geonames. Just go to http://www.geonames.org/login with your favorite browser, sign up as a new user, and confirm it when you receive a confirmation e-mail. It may seem that everything has been done, however, you still need to upgrade your account to use the API services. Don't worry, it's free! So, open http://www.geonames.org/manageaccount and upgrade your account.

With geonames, we can receive information on cities by their coordinates, but we don't have the weather forecast and pictures. For weather forecasts, open http://openweathermap.org/register and register a new user and API.

Lastly, we need a service for the cities' pictures. In this case, we are going to use Flickr. Just create a Yahoo! account and create an API key at https...

Create a project group (command + option + N) for the view controllers and move the ViewController.swift file (created by Xcode) to this group. As we are going to have more than one view controller, it would also be a good idea to rename it to InitialViewController.swift:

Now, open this file and rename its class from ViewController to InitialViewController:

class InitialViewController: UIViewController {

Once the class is renamed, we need to update the corresponding view controller in the storyboard by:

The following picture demonstrates where you should do this change and how it should be after the change:

Great! Now, we can draw the scene. Firstly, let's change...

The next step is to create a class to store the information received from the Internet. In this case, we can do it in a straightforward manner by copying the JSON object properties in our class properties. Create a new group called Models and, inside it, a file called CityInfo.swift. There you can code CityInfo as follows:

class CityInfo {
    var fcodeName:String?
    var wikipedia:String?
    var geonameId: Int!
    var population:Int?
    var countrycode:String?
    var fclName:String?
    var lat : Double!
    var lng: Double!
    var fcode: String?
    var toponymName:String?
    var name:String!
    var fcl:String?
    
    init?(json:JSON){){){
        // if any required field is missing we must not create the object.
        if let name = json["name"].string,,, geonameId = json["geonameId"].int, lat = json["lat"].double,
            lng = json["lng"].double {
            self.name = name
            self.geonameId = geonameId
            self.lat...

The InitialViewController class will display the possible cities where the user is located. Let's continue with the InitialViewController class and complete its code. To complete this code, we need to think about where we are going to store the received information. We will need two arrays of CityInfo: one is to store every object received from the server and the other is to store the objects that are shown after the user's filter. These arrays must be stored as properties:

    private var cities = [CityInfo]()
    private var citiesDisplayed = [CityInfo]()

At this point, we can complete the didUpdateLocations method, which belongs to the CLLocationManagerDelegate protocol. Now, we can request information of the cities that are around us. Type the following code to implement the didUpdateLocations method, replacing the yourgeonamesuser word with the username you registered on geonames:

    func locationManager(manager: CLLocationManager!, didUpdateLocations...