Accessing the Camera & Displaying Photos

Learning Goals

• Access a user’s camera or photo library on an iOS device

Technical Vocabulary

• inherit
• source type
• actions
• outlets
• dictionary

Setup

If you plan to code-along for this lesson, you’ll need a small project set up that looks similar to this:

It should have one Image View and two buttons.

Privacy

Have you ever had an app pause before you were able to use a certain feature and ask a question like this?

To access a user’s data - whether it be from the microphone, camera, health info, etc., an app has to have the permission from a user. Apple designs the way these little boxes appear, provides us with the buttons, and handles them as necessary when tapped. But we have to go in and tell the app “Please get the users permission for XYZ” Today, we need to get the user’s permission to access their camera and photo library.

Info.plist

To tell the app that we want to ask for permission for the camera, we need to find the Info.plist file within our project on the Navigation Pane.

Click on the top row - Information Property List, click the small plus sign, and it will create a new row. Under Key, select Privacy - Camera Usage ..., then under Value, type in a short message explaining how the camera will be used.

Once you set this up in your project, it is set up forever and you should never need to some back to this page (unless you have other permissions to tell the app about!)

UIImagePickerController

Let’s break the documentation down:

When we see this view controller - this tells us this a view controller, or the code behind a storyboard, in which Apple has already written all the code for. It’s a ‘freebie’! Manages the system interface - interface is referring to anytime more than one program works together. We know that a program is just code, so this means that different pieces of code are coming together to make this view controller. ... for taking pictures, etc. tells us what use this view controller has. The name ImagePicker should provide a hint, but reading the documentation carefully to make sure we are working with what we really want to work with is important.

Now we get a little more info: we get these code snippets that tell us what code we will need to write to use (interface with) the code apple gives us. This also shows how to specifically access the camera vs. the photoLibrary!

Access the Camera - Setup

We need to do a little set up. Our class needs to inherit, or take in the information that two apple classes have - UIImagePickerControllerDelegate and UINavigationControllerDelegate.

We already know about UIImagePickerController. The Delegate added on tells the program, whenever I get information from the camera, this delegate class is the place I will send that information back to (information being the photo selected/taken). The UINavigationControllerDelegate is what allows us to navigate from our screen to the camera screen. Behind the scenes, it’s a seque, just written with code rather than the segue’s we’ve seen with the arrows on the storyboard.

Step 1. Inherit from UIImagePickerControllerDelegate and UINavigationControllerDelegate (line 11/12)

Then, we need to create a property (variable) in this class. The value of it will store an object created from UIImagePickerController

Step 2. Create an object from UIImagePickerController class, stored in variable (line 13)

Last, in the viewDidLoad function, which runs each time the view loads, we need to tell the imagePicker, or object from UIImagePickerController that it needs to send, or delegate, information back to this class (self).

Step 3. Tell that object to give it’s information to this class (line 17)

Access the Camera - Button Tap

Now, we need to establish an action and write some code so that when the Take Selfie and Choose From Library buttons are tapped, they take us to the camera and library, respectively.

Establish an action in the code.

Step 1. Establish an action between the Take Selfie button and ViewController.swift

When we tap this button, our plan is that the camera will open up for our user to take a photo.

Step 2. Tell the app to go into the camera (via sourceType)

Step 3. Present the imagePicker!

The code will look like this:

On Line 22 in the screenshot above, we are giving the following directions: “go into the object from that UIImagePickerController, and select the sourceType of camera.”

On line 24, we are giving the following directions: “stop showing whatever you are showing, and present (show) the view where the user can see their camera!” The present function is built in, and take three arguments:

1. What do you want me to show? In this case, imagePicker.
2. animated: Do you want a smooth animation? We will usually say yes here.
3. completion: Once this is complete, do you want me to do anything else? We will always say nil (meaning, no) here.

Run on Device

Now is the moment of truth. Before you press play, make sure the device is plugged into the laptop and is selected as the device to run on.

Run the app. As a user, you should…

• See the permissions message
• Click Take Selfie and be taken into the camera
• Take a selfie
• Click select, or re-take and be able to re-take

NOTE: Occasionally, the permissions message doesn’t appear (and it only appears one time); if you don’t see it, don’t panic.

What happens once you select a picture?

We wrote code to access the camera when the takeSelfieTapped button was tapped, but we haven’t provided the app with directions for what to do with the selected photo.

Before we move on to do that, make sure you can also access the Photo Library.

Displaying Photos

Like we’ve seen, we’re able to access the camera and photo library. It’s now time to write some code so that our user sees the photo they selected on that original screen!

Create an Outlet

First, since that Image is an object that we want to keep track of, we need to create an outlet for it.

Now, we will use another built-in Swift function called imagePickerController. The cool thing about this function is that it will automatically run when the user selects a photo from the camera or library; we never have to call it.

We do however, need to write code inside of that function where we will need to provide the directions to display that photo that has been selected!

Pro-Tip: If you start typing imagePickerController, Xcode should auto-complete the whole setup of this function for you.

We want the user to be taken back to the screen where they can see their photo in that space from answer # 1.</p>

The two things that need to happen when this functions runs are:

1. Update our photo with the photo the user selected
2. Go to back our ViewController so the user can see the update

Update our photo with the photo the user selected

The blue annotations in the screen shot above point out how we will access the photo that was selected. The imagePickerController takes an argument, called info, which is a dictionary. That info dictionary holds the selected photo.

Check out the code below:

On line 26, we have an if let to unwrap the UIImagePickerController.InfoKey.originalImage value in the dictionary. That’s really long, but what it’s doing is accessing the photo the user selected.

On line 27, we are reassigning the image property on the newImage variable to the photo the user selected!

Go to back our ViewController

Our last step is to take the user back to our ViewController so they can actually see the updated photo!

What actually happened when the photo picker appeared, was that it slid in on top of our ViewController. So we need to slide it off, which will allow the user to see our ViewController again. You can think of it as layers, like this:

We need to dismiss the photo picker. Let’s add the following to our action/function:

imagePicker.dismiss(animated: true, completion: nil)

The dismiss function is another built-in function that Apple gives us. It takes an argument of animated and completion. Like we’ve done before, give animated: true and completion: nil. If you’re wondering what animated does, try changing it to false and see what happens!

Now, let’s run this is in the simulator or on a device - it should work!