All about Working with Xcode Previews

Publish date: 2024-05-03

In the realm of iPhone app development, there exists a powerful yet elusive tool known as Xcode Previews. It holds the potential to revolutionize the way teams design, iterate, and test user interfaces. 

With its real-time feedback and dynamic visualization capabilities, Xcode Previews offer a glimpse into the future of app development. Its significance extends beyond just the industry leading Apple device and app ecosystem.

New iOS apps are released regularly with steady numbers every month which makes it essential to use XCode Previews to deliver high quality iOS apps.

Apple app release trendsApple app release trends shows consistency and strong volumes

As Android and Web UI developers look at Xcode with envy and frustration, trying to find analogous features within their own ecosystems, they willingly or unwillingly give credence to the desirable features offered by Xcode Previews.

Let’s dive right into the details.

Table of Contents

What is Xcode Previews?

Xcode Previews is a feature introduced in Xcode 11 +, Apple’s integrated development environment (IDE) for macOS, used for developing applications for Apple platforms i.e. iOS, iPadOS, macOS, watchOS and tvOS. 

Xcode Previews allows developers to see real-time previews of their user interfaces (UI) and interact with them directly in the Xcode editor without running the entire application as a finalized bundle (.ipa etc.).

With Xcode Previews, developers can create and modify SwiftUI views, which are user interface components, and see the changes immediately in the Preview canvas.

When to use Xcode Previews?

Xcode Previews can be used in various scenarios during the development of Apple platform applications. Here are a few situations where Xcode Previews can be particularly beneficial:

1. Building User Interfaces

2. Dynamic UI Testing

3. Responsive Design

4. Rapid Prototyping

5. Collaboration 

Xcode Previews enhances productivity, speeds up the development cycle, and improves the overall quality of Apple platform applications.

How to use Xcode Previews?

Here are the ways that you can use to create XCode Previews, Work with the XCode Previews, and variations in XCode Previews.

Creating Previews

To create an Xcode preview you don’t have to perform extra steps.

1. Create a new Xcode project, or open an existing one.

Create new XCode Project for Creating XCode Previews

2. The Project configuration window will show up.

XCode Project Configuration Window

3. Create a new SwiftUI file or open an existing one in Xcode.

Create a new SwiftUI file for Creating XCode Previews
At the bottom of the file, Xcode automatically inserts a preview structure. Configure this structure as needed. For Example, this is the default ‘View’ upon creating a new project inside Xcode:

 
import SwiftUI
 
struct ContentView: View {
 
    var body: some View {
 
        VStack {
 
            Image(systemName: “globe”)
 
                .imageScale(.large)
 
                .foregroundColor(.accentColor)
 
            Text(“Hello, world!”)
 
        }
 
        .padding()
 
    }
 
}
 
struct ContentView_Previews: PreviewProvider {
 
    static var previews: some View {
 
        ContentView()
 
    }
 
}

4. Preview can take few seconds or minutes to load, depending on your computer.

Creating XCode Preview

For the purpose of this demonstration, lets add a few UI components:

This is just to populate the screen (not worrying about functionality here). Updated ‘View’ becomes: 

 
import SwiftUI
 
struct ContentView: View {
 
    @State private var name: String = “”
 
    @State private var selectedOption: String = “”
 
    
 
    var body: some View {
 
        VStack {
 
            Image(systemName: “globe”)
 
                .imageScale(.large)
 
                .foregroundColor(.accentColor)
 
                .padding(.bottom, 20) // Update image position
 
            
 
            Text(“Hello, \(name)!”) // Update text
 
                .font(.largeTitle)
 
                .foregroundColor(.primary)
 
                .padding(.bottom, 20) // Update text position
 
            
 
            TextField(“Enter your name”, text: $name)
 
                .padding()
 
                .textFieldStyle(RoundedBorderTextFieldStyle())
 
                .padding(.bottom, 20) // Add input field
 
            
 
            Picker(“Select an option”, selection: $selectedOption) { // Add dropdown
 
                Text(“Option 1”).tag(“Option 1”)
 
                Text(“Option 2”).tag(“Option 2”)
 
                Text(“Option 3”).tag(“Option 3”)
 
            }
 
            .pickerStyle(SegmentedPickerStyle())
 
            .padding(.bottom, 20)
 
            
 
            Button(action: {
 
                // Add button action
 
            }) {
 
                Text(“Submit”)
 
                    .font(.headline)
 
                    .foregroundColor(.white)
 
                    .padding()
 
                    .background(Color.blue)
 
                    .cornerRadius(10)
 
            }
 
        }
 
        .padding()
 
    }
 
}

UI Testing using XCode Previews

Working with Previews

Let’s add the following devices as previews inside our PreviewProvider: 

Updated ‘ContentView_Previews’ looks like this :

 
struct ContentView_Previews: PreviewProvider {
 
    static var previews: some View {
 
        Group {
 
            ContentView()
 
                .previewDevice(PreviewDevice(rawValue: “iPhone 12”))
 
                .previewDisplayName(“iPhone 12”)
 
            
 
            ContentView()
 
                .previewDevice(PreviewDevice(rawValue: “iPad (9th generation)”))
 
                .previewDisplayName(“iPad”)
 
            
 
            ContentView()
 
                .previewDevice(PreviewDevice(rawValue: “Apple Watch Series 7 – 45mm”))
 
                .previewDisplayName(“Apple Watch”)
 
            
 
            ContentView()
 
                .previewDevice(PreviewDevice(rawValue: “Apple TV”))
 
                .previewDisplayName(“Apple TV”)
 
        }
 
    }
 
}

XCode Previews on iPhone 12

Please note that in order for these devices to actually work properly as previews, you need to add the right ‘Targets’ and download necessary files. 

Now consider you want to have views based on custom criteria, not limited to form-factors offered by Apple. For example, let’s add variations to manually adjust the previews for these scenarios:

Updated code:

 
struct ContentView_Previews: PreviewProvider {
 
    static var previews: some View {
 
        Group {
 
            ContentView()
 
                .previewLayout(.sizeThatFits)
 
                .previewDisplayName(“Size That Fits”)
 
            
 
            ContentView()
 
                .previewLayout(.fixed(width: 400, height: 800))
 
                .previewDisplayName(“Custom Size”)
 
            
 
            ContentView()
 
                .previewLayout(.fixed(width: 800, height: 400))
 
                .previewInterfaceOrientation(.landscapeRight)
 
                .previewDisplayName(“Landscape”)
 
        }
 
    }
 
}

XCode Previews on iPad 9th generation

Variations in Previews

Additionally, here are some commonly occurring iPhone app UI development scenarios and techniques you can use with Xcode previews:

These techniques will help you handle various scenarios and ensure that your app’s UI looks and behaves correctly on different devices, settings.

Please note that this was just a basic example of using Xcode Previews for iPhone App Development. 

Advantages of using Xcode Previews

Using the Xcode previews feature offers several advantages for developing iOS apps:

Limitations of Xcode Previews

While Xcode previews offer many benefits, it’s important to be aware of their limitations:

Test iOS Apps on Real Devices with BrowserStack App Live

Despite these limitations, Xcode previews remain a valuable tool for visualizing and iterating on UI components during development. 

It’s recommended to combine previews with other testing techniques to achieve comprehensive coverage and ensure the overall quality of your app.

Testing Xcode Previews on real devices

Testing Xcode previews on real devices could be an expensive and time consuming task. But it is majorly simplified by BrowserStack’s Device Cloud and App Live services. Here’s how it can help teams better manage testing on real devices:

Test on Real Devices with BrowserStack App Live

Select Devices to test iOS apps

Real Time Debugging with BrowserStack App Live

Conclusion

Xcode previews offer powerful tools for iOS developers to design, iterate, and test UI. They provide real-time feedback, enhancing productivity. However, they have limitations and should be supplemented with other tests. 

BrowserStack App Live helps test previews on real devices, enabling interactive debugging, multi-device synchronization, and collaboration. It offers a scalable cloud-based infrastructure for all your app testing needs. 

Try BrowserStack App Live Now

Ultimately, Xcode Previews and App Live help streamline UI development, improve app quality, and deliver great user experiences on Apple devices.

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