05. Objects in Apps

Object-oriented programming, as the name implies, relies on the concept of objects. Recall that objects are a way to organize data and functionality into something we can use as programmers. Also, relationships describe how objects are connected and used together within a system. Most importantly, Swift was designed with object-oriented programming in mind—so you'll be using objects!

Up to this point, we’ve examined objects and relationships in the Maze app, but what about real-world apps? In the upcoming exercises, we'll take a look at a few examples.

Prepare

The first app we are going to look at is Airbnb. Airbnb is a trusted community marketplace for people to list, discover, and book unique accommodations around the world, and it services millions of users from all over the world. Below are a few screens from the Airbnb app for the iPhone:

On the first screen, we notice a list of popular travel destinations. Then, when a destination is selected, we see that a destination can consist of many rooms. Also, there are some screens that provide details about a single room. Those screens show information like the room's host and its ratings. These are all great insights!

By just observing a few images, we've already identified four potential objects (destinations, rooms, hosts, ratings) and relationships in the Airbnb app. This process of breaking a large object like Airbnb into smaller pieces is sometimes referred to as decomposition or "object decomposition".

QUESTION:

As an exercise, continue this process and create an object diagram for the Airbnb app. Use the image above or even download/use the app to get an idea of the objects and relationships that might exist in Airbnb. Keep in mind that there is no perfect answer. Just add as much detail as you can. More detail is highly encouraged!

When you're done with your diagram, reflect on what object you think might be the most complex and why. Once you've submitted your answer, you'll be able to compare your diagram with ours!

QUESTION:

What do you notice about our object diagram compared to yours? You must answer the previous question to see our object diagram.

Are there any similarities? Any differences? Is there anything that should be added to the diagram? Does this diagram give you an idea of how the app is built?

Prepare

The next app we are going to look at is Blue Apron. Blue Apron is an app tailored for home cooks who want fresh ingredients delivered to their door. It also features simple, seasonal recipes, cooking instructions, tips, and a marketplace for purchasing cooking equipment.

Again, if you would like, try downloading and using the Blue Apron app to get a better idea of how it works.

QUESTION:

Just like you did with Airbnb, create an object diagram that identifies some of the objects and relationships in Blue Apron. Keep in mind that there is no perfect answer. Just add as much detail as you can. More detail is highly encouraged!

When you're done with your diagram, reflect on what you think might be the most complex object and why. Once you've submitted your answer, you'll be able to compare your diagram with ours!

QUESTION:

What do you notice about our object diagram compared to yours? You must answer the previous question to see our object diagram.

Are there any similarities? Any differences? Is there anything that should be added to the diagram? Does this diagram give you an idea of how the app is built?

Prepare

For our last exercise, let’s take a look at the game Forest Home. Forest Home is a popular kids game that challenges users to guide forest animals back to their homes.

This time if you don’t have an iOS device readily available, there is a trailer you can watch to get an idea of the game.

QUESTION:

As with the previous two exercises, build a diagram representing the objects and structures in Forest Home. When you are finished, post an image of your favorite diagram in the forums.

Keep in mind that there is no perfect answer. Just add as much detail as you can. More detail is highly encouraged!

When you're done with your diagram, reflect on what object you think might be the most complex and why. Once you've submitted your answer, you'll be able to compare your diagram with ours!

QUESTION:

What do you notice about our object diagram compared to yours? You must answer the previous question to see our object diagram.

Are there any similarities? Any differences? Is there anything that should be added to the diagram? Does this diagram give you an idea of how the app is built?