UPGRADE YOUR SKILLS: Learn advanced Swift and SwiftUI on Hacking with Swift+! >>

View composition

Paul Hudson    @twostraws   

SwiftUI lets us break complex views down into smaller views without incurring much if any performance impact. This means that we can split up one large view into multiple smaller views, and SwiftUI takes care of reassembling them for us.

For example, in this view we have a particular way of styling text views – they have a large font, some padding, foreground and background colors, plus a capsule shape:

struct ContentView: View {
    var body: some View {
        VStack(spacing: 10) {
            Text("First")
                .font(.largeTitle)
                .padding()
                .foregroundStyle(.white)
                .background(.blue)
                .clipShape(.capsule)

            Text("Second")
                .font(.largeTitle)
                .padding()
                .foregroundStyle(.white)
                .background(.blue)
                .clipShape(.capsule)
        }
    }
}

Because those two text views are identical apart from their text, we can wrap them up in a new custom view, like this:

struct CapsuleText: View {
    var text: String

    var body: some View {
        Text(text)
            .font(.largeTitle)
            .padding()
            .foregroundStyle(.white)
            .background(.blue)
            .clipShape(.capsule)
    }
}

We can then use that CapsuleText view inside our original view, like this:

struct ContentView: View {
    var body: some View {
        VStack(spacing: 10) {
            CapsuleText(text: "First")
            CapsuleText(text: "Second")
        }
    }
}

Of course, we can also store some modifiers in the view and customize others when we use them. For example, if we removed foregroundStyle() from CapsuleText, we could then apply custom colors when creating instances of that view like this:

VStack(spacing: 10) {
    CapsuleText(text: "First")
        .foregroundStyle(.white)
    CapsuleText(text: "Second")
        .foregroundStyle(.yellow)
}

Don’t worry about performance issues here – it’s extremely efficient to break up SwiftUI views in this way.

Hacking with Swift is sponsored by RevenueCat

SPONSORED Take the pain out of configuring and testing your paywalls. RevenueCat's Paywalls allow you to remotely configure your entire paywall view without any code changes or app updates.

Learn more here

Sponsor Hacking with Swift and reach the world's largest Swift community!

BUY OUR BOOKS
Buy Pro Swift Buy Pro SwiftUI Buy Swift Design Patterns Buy Testing Swift Buy Hacking with iOS Buy Swift Coding Challenges Buy Swift on Sundays Volume One Buy Server-Side Swift Buy Advanced iOS Volume One Buy Advanced iOS Volume Two Buy Advanced iOS Volume Three Buy Hacking with watchOS Buy Hacking with tvOS Buy Hacking with macOS Buy Dive Into SpriteKit Buy Swift in Sixty Seconds Buy Objective-C for Swift Developers Buy Beyond Code

Was this page useful? Let us know!

Average rating: 4.9/5

 
Unknown user

You are not logged in

Log in or create account
 

Link copied to your pasteboard.