When starting the app, the user sees a list of to-do items. The items in the list consist of a title, an optional location, and the due date. New items can be added to the list by an add (+) button, which is shown in the navigation bar of the view. The task list view will look like this:

User stories:

• As a user, I want to see the list of to-do items when I open the app
• As a user, I want to add to-do items to the list

In a to-do list app, the user will obviously need to be able to check items when they are finished. The checked items are shown below the unchecked items, and it is possible to uncheck them again. The app uses the Delete button in the UI of UITableView to check and uncheck items. Checked items will be put at the end of the list in a section with the Finished header. The user can also delete all the items from the list by tapping the Trash button...

The task detail view shows all the information that's stored for a to-do item. The information consists of a title, due date, location (name and address), and a description. If an address is given, a map with an address is shown. The detail view also allows checking the item as finished. The detail view looks like this:

User stories:

• As a user, given that I have tapped a to-do item in the list, I want to see its details
• As a user, I want to check a to-do item from its details view

When the user selects the add (+) button in the list view, the task input view is shown. The user can add information for the task. Only the title is required. The Save button can only be selected when a title is given. It is not possible to add a task that is already on the list. The Cancel button dismisses the view. The task input view will look like this:

User stories:

• As a user, given that I tapped the add (+) button in the item list, I want to see a form to put in the details (title, optional date, optional location name, optional address, and optional description) of a to-do item
• As a user, I want to add a to-do item to the list of to-do items by tapping on the Save button

We will not implement the editing and deletion of tasks. But, when you have worked through this book completely, it will be easy for you to add this feature yourself by writing the...

The following diagram shows the structure of the app:

In iOS apps, data is often presented using a table view. Table views are highly optimized for performance; they are easy to use and to implement. We will use a table view for the list of to-do items.

A table view is usually represented by UITableViewController, which is also the data source and delegate for the table view. This often leads to a massive table view controller, because it is doing too much: presenting the view, navigating to other view controllers, and managing the presentation of the data in the table view.

Sometimes, it's a good idea to split up the responsibility...

Now, let's start our journey by creating a project that we will implement using TDD.

Open Xcode and create a new iOS project using the Single View Application template. In the options window, add ToDo as the product name, select Swift as language, and check the box next to Include Unit Tests. Let the Use Core Data and Include UI Tests boxes stay unchecked.

Xcode creates a small iOS project with two targets: one for the implementation code and the other for the unit tests. The template contains code that presents a single view on screen. We could have chosen to start with the master-detail application template because the app will show a master and a detail view. However, we have chosen the Single View Application template because it comes with hardly any code. In TDD, we want to have all the implementation code demanded by failing tests.

To take...

Xcode has a feature called behaviors. With the use of behaviors and tabs, Xcode can show useful information depending on its state.

Open the Behaviors window by navigating to Xcode | Behaviors | Edit Behaviors. On the left-hand side are the different stages for which you can add behaviors (Build, Testing, Running, and so on). The following behaviors are useful when doing TDD.

The behaviors shown here are those that I find useful. Play around with the settings to find the ones most useful for you. Overall, I recommend using behaviors because I think they speed up development.

When the building starts, Xcode compiles the files and links them together. To see...

In this chapter, we took a look at the app that we are going to build throughout the course of this book. We took a look at how the screens of the app will look when we are finished with it. We created the project that we will use later on and learned about Xcode behaviors.

In the next chapter, we will develop the data model of the app using TDD. We will use structs for the model wherever we can, because models are best represented in Swift by value types. We will add some conformance to the Equatable protocol to make the comparison of the model instances easier.