In this tutorial, we will look at how to create a list app for iOS. The example used in this tutorial will be a list of cities. When the name of a city in the list is tapped by the user, details about that city will be presented (we will achieve that part in the next tutorial).
Begin by clicking File > New Solution in Xamarin Studio and then select iOS App and Single View App. Then click Next.
Give the app a name (the app in this example will be called ListAppIOS), select the target iOS version and then click Next.
Confirm the project name, solution name, project location and click Create.
Open the Main.storyboard file and select an iPhone model from the View As drop-down list (eg. iPhone 6). Then drag a Table View Controller on to the storyboard next to the main screen.
Now right-click on the main screen (on the left) and select Delete to remove this screen as it is no longer needed (you may need to click Delete twice). The Table View controller will now be the first screen that loads when the app launches.
Now that the first screen is deleted, the ViewController.cs file will no longer be needed so we can delete it. Select the ViewController.cs file, right-click it and select Remove.
Then select Delete when the dialog box appears asking you.
Now you will need a class that will control the table view controller. Select the Table View Controller by clicking on the bar at the bottom of it. You should see the Class property on the Properties panel. At the moment it is empty but it needs a class so we can create the class here.
Click in the Class property field and type in a name for the new class eg. CitiesViewController. Then press Enter. You’ll notice a new C Sharp (.cs) file is created for this new class and it will appear in the solution panel.
At this stage, if you simulate the app you will see an empty list on the main screen as shown below.
Now go back to the Main.storyboard file and click on the title bar at the top of the app screen. We need to add a reuse identifier that allows the app to re-use rows on the table on the app screen as the user scrolls down the screen rather than having to generate new rows. Change the Identifier value to City.
Now open the CitiesViewController.cs file so that you can start populating a list of cities in the table view controller. Adding the using System.Collections.Generic; line allows us to use the List class that can contain many elements. Before we start creating a list of cities we need to define what a city is by creating a City class and giving it some properties such as its name (string), the country and state it belongs to (strings) and its population (integer).
Once we have created the class City, we can create a List that will contain many elements and set its type to City so that every time added to the list will be a city. First we give the list its name and set its type, and then we can create the list.
Now that we have create the list, we can populate the table view with data from the list.
Now we need to override a few of methods: NumberofSections, RowsInSection, and GetCell. For each method, as you type public override and press the spacebar key, you will be presented with methods that you can select from. Start typing the name of the method you want to override and then double-click it to add the override method.
The first method we override is NumberofSections which can be set to return 1 because only one section is needed in the table. As shown below on line 36, we set return to 1.
The second method is RowsInList which is set to return CityList.Count; (this will make as many rows in the table as there are cities in the list) as seen on line 41.
The third method we override is GetCell which is the method that will allows us to get a re-usable cell, modify its values, and return it to the table view. We create a variable called cell and we use the name of the reuse identifier we set for the table view controller back in Step 8 (line 46). We also create a variable called data which set each row to contain data from the city list (line 47) and we set the text on the TextLabel (a default TextLabel already exists) for the cell to be the name of the city for that row (line 48). Lastly, we return cell (line 49).
Here are the three methods once they have been added.
At this stage, if you test the app in the simulator you will see the list with the name of each city on each row of the list (we only have two rows in this list but you can add many more to your list).
Now we need to customised the rows in the list to improve their appearance and so they can display some more information about each city.
Now we will add more details to each row in the table view (the state and country). Open the Main.storyboard file and click once on the row at the top of the table view. Go to the Class field. We will create a class that will represent the row.
The Class field should currently say UITableViewCell (if it says UITableView, then you may have clicked twice on the row on the screen. De-select the row, then click it once making sure that that the Class field says CityTableViewCell. Type in CityTableViewCell in the Class field and press the Enter key on the keyboard.
You should now see the CityTableViewCell.cs file in the solution panel. Double-click it to open the file – we will now start adding code to this new C Sharp file.
Now we need to create a local private variable called City just for this class. Then we need to create a global variable for this data so it can be accessed anywhere. In this, we will have a getter which will get the method that we will access the value of the property (it will return bookData – the private property). Then we set the bookData to the value we are getting.
Go back to the Main.storyboard file. Drag a Label element on to the row at the top of the screen.
Resize the row at the top of the screen because it will need to fit more labels by dragging it down from the circle at the bottom of the row.
Now add more Label elements to the screen to display the city name, state name, country name, and population. Arrange and resize the labels so they will be able to fit their text in. Give each label a default property for Text so that you know what each label represents. You can also change the colours or font style. For example, the city name label below is set to Size 19pt Semibold.
Change the Name property for each Label. The labels on this screen have the following names:
- cityNameLabel (this will display the city name)
- stateCountryLabel (this will display the state and country separated by a comma)
- populationLabel (this will display the city’s population)
Go back to the CityTableViewCell.cs file. We now need to access the labels from the screen that we created in Step 16 and set the text on the labels to match the properties from cityData when the the cityData property receives its value. Add the lines of code below and then save the file.
Note that the state and country are added together with a comma and space in between them. Also note the #,##0 inside the ToString() brackets – this will place commas between the hundreds and thousands for population when displayed on the populationLabel to improve formatting.
Go back to the CitiesViewController.cs file. Instead of simply getting a cell, we will now get a cell as CityTableViewCell so we need to add the extra code to the GetCell method as highlighted on line 46 of the code below.
We also need to change the code so that instead of having cell.TextLabel.Text = data.Name; we will now just have cell.cityData = data;
This means we are no longer accessing a property of the data but instead we are just passing the city. Now it is time to test the app. When you test your app in the simulator you may notice some problems with the formatting of your rows such as the row height or overlapping text as seen below. We will look at how to fix this in the next step.
After testing, you may realise that you need to change the font size for labels, label width/height, or placement of labels. You may also see overlapping text or items that appear to be in the wrong row. If you see this, you may need to adjust the row height. Click on the Table View (not the row) and then click on the Layout tab on the Properties panel. Under Table View Size, change the Row Height value to something more suitable and test your app. Keep adjusting the value and testing as needed. In this example app, the Row Height value has been changed to 115.
That’s it! Now you can go and test your app! If you want to add a detail screen for each item in the list, then check out the next tutorial.