iOS Tutorial

This iOS Tutorial is an introduction to the Xojo development environment and will lead you through the development of a real iOS app. It should take you 30 to 45 minutes to complete this tutorial. We'll walk you through building a Task Manager app from start to finish. If you are new to programming and to Xojo, we recommend you first complete the iOS QuickStart.

iOS development requirements

A Mac is required to develop iOS projects with Xojo. To run/test/debug an iOS project you create in Xojo requires the iOS Simulator which is provided with Apple's Xcode development tool. You can download Xcode for free from the Mac App Store. After you have downloaded and installed Xcode, you need to run it one time to accept its License Agreement. After doing that, you can quit Xcode and will never have to use it again as Xojo will automatically launch the iOS Simulator for you. If you have not yet downloaded and installed Xcode, do that now before continuing with the tutorial.

Getting started

1. Launch Xojo. After it finishes loading, the Project Chooser window appears. If Xojo is already running, choose File > New Project.

Xojo lets you build several different types of apps (Desktop, Web, Console and iOS).

2. For this Tutorial, you are building an iOS app, so click on iOS.

You should now see three fields that need values: Application Name, Company Name and Application Identifier.

• Application Name: the name of your app. This will be the filename of the actual app file that gets created.

• Company Name: the name of your company.

• Application Identifier: a unique identifier for this app. It will automatically populate using what you enter for the Application and Company Names, but you can also change it to whatever you want.

3. Enter TaskManager as the Application Name.

4. Click Create to open the main Xojo window (called the Workspace) where you will begin designing your app.

The Workspace

Xojo opens the Workspace with the default View for your app selected in the Navigator and displayed in the Layout Editor.

• Navigator: The area on the top left shows you all the items in your project. By default you can see Screen1 (which is selected), the App object, the iPhone and iPad Layout objects and items for the App Icon and optional Launch Screen. You use the Navigator to navigate within your project.

• Layout Editor: The center area is the Layout Editor. You use the Layout Editor to design the user interface for the Screens in your app. It shows the Screen and previews how it looks when the app runs on an iOS device. In this image, the Screen is blank because you haven't yet added any user interface controls from the Library.

• Library: The area on the right is the Library and shows the controls and interface elements that you can add to a Screen or to the project. You design the Screen by dragging controls from the Library to the Screen layout. You can also add a control to the Screen by double-clicking it. You can change how the controls display in the Library by clicking the small gear icon and choosing a different setting.

If the Library is not visible, click the Library button on the toolbar to show it.

Inspector: Not shown in the above image is the Inspector, which allows you to see and change the properties for the selected control. This area of the Workspace window is shared with the Library. You can show the Inspector by clicking the Inspector button on the toolbar. The Inspector shows information about the selected item in the Navigator or Editor. The contents of the Inspector changes as you click on different items. You change an Inspector value by entering a new value in the field to the right of the field label.

About the app

In this tutorial you will create an app to manage tasks. Not surprisingly it is called Task Manager. When finished, the app will let you add tasks, mark them as completed (and unmark them if it turns out they are not) and delete them.

Task manager

For the Task manager app, you enter tasks in the text field and tap Add to add them to the table. You can tap on individual tasks in the table to delete them or mark them as complete.

Task Manager uses these controls:

Icon	Name	Description
	TextField	A TextField control is used to enter text. In this project, the task to add is entered into an TextField at the top of the Screen.
	Button	A Button is used to trigger an action. This project uses a Button to add a task to the table.
	Table	A Table is used to display a list of data. In this project, it is what displays the tasks entered in the TextField.

Designing the user interface

Xojo is displaying Screen1 open in the Layout Editor. You are now going to add the controls to the Screen and position them.

Adding a button

First add the Button that is used to add a task to the table.

1. In the Library, click on Button and drag it to the Screen so that it is at the top right just below the Navigation Bar.

2. Use the alignment guides to position it with the appropriate amount of space between the header line and the right edge of the Screen.

Adding a text field

The TextField is where the user types the Task to add to the list.

1. In the Library, click on TextField and drag it to the Screen so that it is at the top left just below the Navigation Bar. As you drag you will notice alignment guides that will help you align the TextField with the Button as pictured below.

2. Grab the right handle of the TextField and drag it to make the control wider until you reach the button's left alignment guide.

Adding a table

The Table displays the tasks.

1. In the Library, click on the Table and drag it to the center of the Layout Editor below the Button and TextField. As you drag the Table onto the Screen, you will see alignment indicators that help you position the control. Drop the Table when you are happy with its position on the Screen.

2. Grab the bottom handle of the Table and drag it downward to make it taller. Stop dragging when the bottom edge is right up against the bottom of the Screen:

The screen layout at this point

After adding all the controls, your Screen should now look like this:

Understanding properties

What is a property?

A property is a value of a class. Changing property values allows you to change the behavior of the object. For this project, you want to change various properties for the Screen and the controls you added. Some of the things you need to do are:

• Rename all controls (and the Screen) so that they describe their behavior and are easy to refer to in code.

• Add a Caption to the Button.

• Add a hint to the TextField to help the user know what to enter.

Using the inspector

The Inspector is used to change screen and control properties. It shares the same area on the right of the Workspace as the Library.

1. In order to show the Inspector, click the Inspector button on the toolbar or press ⌘-I on macOS or Ctrl-I on Windows and Linux.

Changing screen properties

You need to change the Name and Title properties of Screen1:

1. In the Layout Editor click anywhere on the background (or phone UI) to select the Screen (rather than a control). The Inspector now shows the properties of the Screen.

2. Change the Name property from Screen1 to TaskManagerScreen. Press Return to see the name change in the Navigator.

3. Change the Title property from Untitled to Task Manager. Press Return to see the name change in the Navigation Bar of the screen.

Changing button properties

For the button you'll change the Name and Caption properties.

1. Click the Button to select it. The Inspector now shows its properties.

2. In the Inspector, change the Name property from Button1 to AddButton. Press Return to see the name change in the Navigator.

3. Change the Caption property from Button to Add.

Changing textfield properties

The TextField is where the user types the task to add to the Table. You'll be changing the Name, Text and Hint properties.

1. Click on the TextField to select it so that its properties are displayed in the Inspector.

2. Change the Name property from TextField1 to TaskField. Press Return to see the name change in the Navigator.

3. Change the Hint property to Enter a task.

4. To make it easier for the user to type, switch on the Allow Spell Checking and Allow Auto Correction properties.

Changing table properties

The table displays the tasks and will also show a check mark next to ones marked as completed. Let's change the Name property to something that is more descriptive.

1. Click on the table to select it and display its properties in the Inspector.

2. Change the Name property from Table1 to TaskTable. Press Return to see the name change in the Navigator.

Note

In the Auto-Layout section of the Inspector, look at the first row. The Edge column has the value Bottom. The Rule column should have the value BottomLayoutGuide.Bottom. If it doesn't, resize the Table control using its bottom handle until that value changes to BottomLayoutGuide.Bottom. This will ensure that the bottom of the table is locked to the bottom of the layout.

The final layout

This is what your layout should now look like after adjusting all the properties:

Running the app

Your user interface layout is now complete, so it's time to try it out. But before you go further, you should first save your work.

1. Save the project by selecting File > Save.

Note

This means select Save from the File menu and is the standard way choosing menu items are notated in the Xojo documentation.

2. Name the project iOSTaskManager and click Save.

To test the app you use the iOS Simulator. To get the iOS Simulator from Apple you'll have to first download, install and run Xcode once so it installs its components. You do not need to keep Xcode running or otherwise use it when developing with Xojo. To learn more about Xcode and the iOS Simulator, refer to the Installing Xcode and Apple Certificates and iOS Simulator topics.

Note

If the iOS Simulator window is quite small the first time you run your app, in the iOS Simulator choose Physical from the Window menu. That will permanently resolve the issue.

Now you can test your app:

1. Click the Run button in the toolbar to run the project. This builds your app and runs it in the iOS Simulator.

2. When your app appears in the iOS Simulator, you can interact with the buttons by clicking on them or you can type in the TextField.

3. When you are finished, switch back to Xojo and click the Stop button.

Of course, Task Manager doesn't do anything yet! For that you need to add some code, which is what you'll do next.

Note

If you want to change the type of iOS device that the iOS Simulator runs your project in, choose Project > Run On then choose another iOS device from the list. You can even run directly on your iPhone or iPad by plugging it into your Mac.

Adding code

To complete the Task Manager, you will need to:

• Make the Add Button add a task.

• Make the Add Button only be enabled after the user has entered text into the TaskField.

• Allow the user to swipe left to mark a task as completed.

• Allow the user to swipe left to delete a row.

Coding the Add button

First, you're going to need to create something in which to store the tasks. Normally you could just add tasks as rows directly to the table. However, because you will want the user to be able to swipe left to mark and delete tasks, you will need to store the data elsewhere. You can do this by adding a property to the Screen. This property will be an array which is a list. Since you need to store both the name of the task and whether or not it's been completed, the array will be an array of Pairs. A Pair in Xojo is two values that go together. The left side of the pair will store the task and the right side will store True (if the task has been completed) and False if it has not. To help you visualize the array, consider the list below with three tasks, the first one which is completed:

Left	Right
Wash the dog	True
Mow the lawn	False
Clean the garage	False

Let's create the array to store the tasks:

1. To add a new property, select Insert > Property. A new property is added to the TaskManagerScreen.

2. In the Inspector, enter Tasks() as the name. The () makes this an array.

3. In the Inspector, enter Pair for the Type.

If you've already done the QuickStart then you know that Events are where you put code that needs to respond to an action such as a user pressing a button. Let's now make the Add button add the task to the Tasks array:

1. In the Navigator, click on the AddButton to select it.

2. In the Layout Editor, double-click the Add button.

3. When the Add Event Handler dialog appears, the Pressed event will already be selected which is the one you want so click OK to add it.

You are now in the Code Editor editing the AddButton's Pressed event. When the user presses the button, the button should add a row to the Tasks array using the text the user entered in the TaskField, store [False] to indicate the task is not yet completed, and clear the contents of the TaskField so they can enter another task.

4. In the Code Editor, enter the following two lines of code:

Tasks.Add(TaskField.Text : False)
TaskField.Text = ""
TaskTable.ReloadDataSource

Note

To save yourself having to do a lot of extra typing, remember that when you see an ellipsis (...) in the Code Editor, pressing the Tab key on your keyboard will auto-complete the item for you.

Arrays have functions built into them, one of which is for adding items. The first line adds the Text from the TaskField and the value False as a pair to the Tasks array. It's the : that makes them a pair. The second line clears the contents of the TaskField so the user can enter another task. The third and final line tells the TaskTable to reload all of its data so the user will see the new task they just entered. The last step to making the Add button work is to connect the Tasks array to the TaskTable control. You will do this by making the TaskManagerScreen the source of the data for the TaskTable so that its Tasks array can provide that data. You will want to do this as soon as the TaskManagerScreen opens. Thus you will use its Opening event:

1. In the Navigator, click on the TaskManagerScreen to select it.

2. Select Insert > Event Handler. The Add Event Handler dialog appears. Since the TaskManagerScreen is selected, the events that appear are for it.

3. The Opening event is selected by default so go ahead and press OK to add it.

4. Enter the following line of code to make the TaskManagerScreen the TaskTable's datasource:

TaskTable.DataSource = Self

The Self function is a generic way of referring to the object item whose method is being called. Because this is the TaskManagerScreen's Opening event, Self refers to the TaskManagerScreen. Next you need to add some methods that will connect the Tasks array to the TaskTable's datasource. This will make it possible for tasks you add to appear in the table. Methods are groups of one or more lines of code that perform a function. If you've written code in other languages, you may have called these subroutines. Normally you can name methods whatever makes sense to you. In this particular case, the datasource has specific method names it will be looking for. A group of methods that allow one thing to interface with another thing is appropriately called an Interface. You will be adding the iOSMobileTableDataSource interface which will create methods that will allow the app to get data from the Tasks array:

1. In the Navigator, click on the TaskManagerScreen to select it.

2. In the Inspector, click on the Choose... button next to Interfaces. 'The Interfaces dialog box appears.

3. Click the checkbox next to iOSMobileTableDataSource.

4. Click OK to add the interface.

Notice that a new list titled "Methods" has appeared in the Navigator. It has four methods: RowCount, RowData, SectionCount and SectionTitle. The TaskTable data source knows these method names and will call them when it needs data from the Tasks array. Your next task (no pun intended) is to enter the code into 3 of these methods that will make them do their jobs:

1. In the Navigator, click on the RowCount method. When the TaskTable needs to know how many rows there are in the array, it will call this method.

2. The line of text that appears is a comment. Click at the end of it then press Return to create a new line.

3. Enter the following code:

Return Tasks.Count

The Return command sends the data right back to whatever called the method. In addition to the built-in Add method you used earlier, there is also a Count function that, as you have already guessed, returns a count of the number of items in the array.

Next, you'll add code to the RowData method to return the task from the array the user selected in the table:

1. In the Navigator, click on the RowData method to select it.

2. It too has a comment so click at the end of the comment then press Return to create a new line.

3. Enter the following code:

Var cell As MobileTableCellData
cell = table.CreateCell(Tasks(row).Left)
Return cell

The first line creates a new variable titled "cell" of type MobileTableCellData. A cell in a table will hold one task. The second uses the table variable that was passed from the TaskTable to the RowData method. You can see this at the top of the Code Editor just above the comment. The Table variable represents the TaskTable in this case. It has a built-in method called CreateCell, which as the name implies, creates a cell. It's expecting the text you want in the cell. Remember, the text of the task is stored in the left property of each Pair in the Tasks array. Fortunately, the RowData method also is passed the row number the user tapped on in the row variable. It too can be seen at the top of the Code Editor. This is then passed to the Tasks array so that it can get the corresponding row from the array. Next use the Left property of the pair to get the name of the task which ultimately is what will be passed to the CreateCell method so that it can create a cell with that task in it. Last but not least, you again use the Return command to return the cell you created to the TaskTable. The last step before you can add tasks is a really easy one. Because Tables can have multiple sections, the TaskTable will want to know how many there are. Since our TaskTable will only have one, you can return 1:

1. In the Navigator, click on the SectionCount method.

2. Click to the right of the comment then press Return to to create a new line.

3. Enter the following code:

Return 1

Great. Let's give it a try.

1. Click the Run button in the main toolbar.

Note

If you mistyped something, instead of the iOS Simulator running, an errors pane will appear in the lower half of the Xojo Workspace window. Should this happen, look at the lines the error messages are indicating and compare them to the code in the instructions above. You probably just mistyped something. If you can't figure it out, go to the Xojo forum or contact us via email.

Your app should now be running again in the iOS Simulator.

2. Type a task in the TaskField and press the Add button to add it to the table. Enter a few tasks if you'd like.

3. When you're done, return to Xojo and press the Stop button you used last time.

Enabling/disabling the Add button

You wouldn't want the user to accidentally add a blank task. To avoid this you'll need to disable the Add button then enable it when the user has entered text in the TaskField, disable it if they clear the TaskField and disable it after the user presses the Add button since this clears the TaskField as well.

1. In the Navigator, click on the TaskManagerScreen to select it.

2. Click on the Add button on the layout.

3. In the Inspector, turn off the AddButton's Enabled property. Notice the button now appears disabled.

4. In the Layout Editor, double-click the TaskField and add the TextChanged event handler.

5. Add the following code to the TextChanged event:

If Me.Text.IsEmpty Then
  AddButton.Enabled = False
Else
  AddButton.Enabled = True
End If

This code checks the Text property of the TaskField to see if it's blank. Me in this case refers to the TaskField since this event is part of that control. If the Text property is blank, the AddButton's Enabled property is set to False. If it's not blank, it's set to True.

Since the Add button clears the TaskField, you need to add a line of code to its Pressed event to disable it after the user presses it:

1. In the Navigator, click on the TaskManagerScreen to select it.

2. In the layout Editor, double-click on the AddButton to go to its Pressed event handler.

3. In the Pressed event, add the following line of code to disable the AddButton:

Me.Enabled = False

The last step is to make it possible for the user to swipe left to mark a task as complete or incomplete and delete it if they wish. Doing this will require:

• Adding another interface to allow row editing

• Adding the Complete/Incomplete and Delete buttons

• Making the buttons perform their functions

Let's do it!

Allowing row editing

1. In the Navigator, click on the TaskManagerScreen to select it.

2. In the Inspector, click the Choose... button next to Interfaces.

3. In the Interfaces dialog box, click the checkbox for iOSMobileTableDataSourceEditing.

4. Click OK to add the interface to the TaskManagerScreen.

5. In the AllowRowEditing method that was just added, add the following code:

Return True

Returning True in this method tells the TaskTable that the user can edit rows.

Adding buttons to a table row

Now let's add the Complete/Incomplete and Delete buttons. To do that you need to add the ApplyActionsForRow event to the TaskTable:

1. Click on the TaskManagerScreen to select it.

2. Double-click on the TaskTable in the Layout Editor to add an event.

3. In the Add Event Dialog Box, choose the ApplyActionsForRow event handler.

4. Click the OK button to add it to the TaskTable.

5. Add the following code to the event:

Var actions(1) As iOSMobileTableRowAction
If Tasks(row).Right Then
  actions(0) = New iOSMobileTableRowAction(_
  iOSMobileTableRowAction.Styles.Normal, "Incomplete", "Incomplete")
Else
  actions(0) = New iOSMobileTableRowAction(_
  iOSMobileTableRowAction.Styles.Normal, "Completed", "Completed")
End If
actions(1)  = New iOSMobileTableRowAction(_
iOSMobileTableRowAction.Styles.Destructive, "Delete", "Delete")
Return actions

Note

In the code above, some of the lines are quite long and would wrap in the PDF version of this tutorial. To avoid this, the _ character appears to break lines into multiple lines. You can copy and paste the code into your project. You can also remove the underscore and put the lines back together if you choose.

So what's going on in this code? The first line creates an array. The size is 1 which creates two items because array numbering begins at 0 rather than 1. The type of each item in the array is iOSMobileTableRowAction. This is an object that represents an action the user can take on a row such as pressing a button. The second line passes the row parameter (which you can see at the top of the Code Editor was passed in to this event) which holds the row number upon which the user tapped. That gets passed in to the Tasks array to get the selected task. You then check the Right property of the Pair. If it's true, that means the task is marked as completed so you want to add the Incomplete button on line 3 allowing the user to remove the checkmark. If it's false, the task is incomplete so you go to line 5 and add the Completed button so the user can tap that to mark it completed. The next line adds the Delete button and finally return the actions array to the TaskTable so it can add them to the row the user swiped left on. Each of these buttons is created using the iOSMobileTableRowAction class. With it you indicate the style of button (Normal provides a gray background while Destructive provides a red one to remind the user that this action will result in data loss). You also pass in the label you want on the button and the action tag you want passed when the user taps the button so you know which action they wish to take. You may be wondering why you need both a button name and action tag when they are the same. Your app might one day be localized into another language in which case the button name would be localized because it's seen by the user but the action tag would not be because only your code uses that.

If you'd like, run your app now and you'll see that you can swipe left to make the Complete and Delete buttons appear. To swipe in the iOS Simulator, press and drag left with the mouse. The buttons don't do anything yet. That's the next step. When you're done, return to Xojo, click the Stop button and get ready for some more coding!

Making the buttons work

Now you need to add the RowActionSelected event to the TaskTable. This event will be called when the user taps on a button after swiping left on a row:

1. In the Navigator, click on the TaskTable to select it.

2. Select Insert > Event Handler. The Add Event Handler dialog box appears.

3. Select the RowActionSelected event.

4. Press OK to add the event to the TaskTable.

5. Add the following code to the RowActionSelected event handler:

Select Case actionTag
Case "Delete"
  Tasks.RemoveRowAt(row)
  Me.ReloadDataSource

Case "Completed"
  Tasks(row) = Tasks(row).Left : True
  TaskTable.ReloadRow(section, row)

Case "Incomplete"
  Tasks(row) = Tasks(row).Left : False
  TaskTable.ReloadRow(section, row)
End Select

When this event is called, the action tag of the action the user chose will be passed in via the actionTag parameter. This code uses a Select Case statement to deal with each possibility.

If the user tapped the Delete button, RemoveRowAt (yet another built-in array method) is called and passed the row number the user tapped on so that it can delete the row from the Tasks array. Then ReloadDataSource is called to cause the TaskTable to update itself with the data from the Tasks array. ReloadDataSource is a built-in method of the table control. If the user tapped the Completed button, the current row of the Tasks array is replaced with the task name it already has and the value True to indicate the task was completed. ReloadRow (another built-in method of the table control) is called to tell the TaskTable to update that row from the Tasks array. If the user tapped the Incomplete button, the exact same thing happens as happened if they clicked the Completed button with the important difference that the value set for the task is False instead of True. In these last two cases, because ReloadRow is called, the RowData method will be called to provide the row data to the TaskTable. That means you have one thing left to do: make the checkmark appear or disappear when the task is completed or marked incomplete.

1. In the Navigator, click on the RowData method to select it. You may need to expand the Methods list to see it.

2. In the Code Editor, click at the end of the line that calls CreateCell and press Return to create an empty line between that line and the Return Cell line.

3. Insert the following lines of code between those lines:

If Tasks(row).Right Then
  cell.AccessoryType = MobileTableCellData.AccessoryTypes.Checkmark
Else
  cell.AccessoryType = MobileTableCellData.AccessoryTypes.None
End If

Your updated version of the RowData method should now look like this:

Var Cell As MobileTableCellData
cell = table.CreateCell(Tasks(row).Left)
If Tasks(row).Right Then
  cell.AccessoryType = MobileTableCellData.AccessoryTypes.Checkmark
Else
  cell.AccessoryType = MobileTableCellData.AccessoryTypes.None
End If
Return cell

As you have already guessed, row is passed to this event from the table and is the row the user tapped on. If the Right value of the task Pair is True, the cell's accessory type (one of several widgets that can appear on the right side of a row) will be set to a checkmark. If it's False, it will be set to nothing. Believe it or not, that's it. Your app is done.

4. Run it in the iOS Simulator and try it out.

Note

Xojo also supports test running and debugging your iOS apps directly on your iPhone or iPad.

Deploying your app

There are several ways to deploy a Xojo iOS app. You can build your app with Xojo and manually copy it to an iOS device using Xcode. Or you can build your app with Xojo and submit it to the App Store. Both of these options require you to create certificates, IDs and distributions profiles with Apple and use Xcode to install them. You can find more information here:

• iOS Device Deployment

• iOS App Store

Next steps

Congratulations, you have successfully completed the iOS Tutorial and now have a fully functional app. You learned a lot in this tutorial. You may be wondering how you'll remember it all. The good news is that you don't have to remember it. Xojo comes with documentation that will help you every step of the way. The User's Guide will give you a general overview of the different parts of Xojo and of all the various controls and things you can use in your projects. The Language Reference will give you the all the details specific controls. After you feel you've reviewed enough of the documentation, choose a small project to build that will benefit you or others. The best way to learn is to have a reason to learn. A small project will provide that. When you need extra help, contact us at hello@xojo.com or go to our helpful community forum.

Download the completed TaskManager project.