What’s new in Xcode 16

3:37 - Inline State within Preview

#Preview {
    @Previewable @State var currentFace = RobotFace.heart
}

3:45 - View using Inline State

RobotFaceSelectorView(currentFace: $currentFace)

3:53 - Complete Preview using Previewable

#Preview {
    @Previewable @State var currentFace = RobotFace.heart
    
    RobotFaceSelectorView(currentFace: $currentFace)
}

4:40 - Type Conforming to PreviewModifier

struct SampleRobotNamer: PreviewModifier {
    typealias Context = RobotNamer

    static func makeSharedContext() async throws -> Context {
        let url = URL(fileURLWithPath: "/tmp/local_names.txt")
        return try await RobotNamer(url: url)
    }
    
    func body(content: Content, context: Context) -> some View {
        content.environment(context)
    }
}

5:29 - Extension on PreviewTrait

extension PreviewTrait where T == Preview.ViewTraits {
    @MainActor static var sampleNamer: Self = .modifier(SampleRobotNamer())
}

5:38 - Preview using created PreviewModifier

#Preview(traits: .sampleNamer) {
    RobotNameSelectorView()
}

10:26 - AVPlayer Creation

struct BOTanistAVPlayer {
    func player(url: URL) throws -> AVPlayer {
        let player = AVPlayer(url: url)

        return player
    }
}

11:28 - AVPlayer Call Site

self.player = try? await robotVideoAVPlayer()

11:57 - AVPlayer Initialization

private nonisolated func robotVideoAVPlayer() async throws -> AVPlayer? {
    guard let url = Bundle.main.url(forResource: RobotVideo.resource, withExtension: RobotVideo.ext) else {
        throw BOTanistAppError.videoNotFound(forResource: RobotVideo.resource, withExtension: RobotVideo.ext)
    }

    let avPlayer = BOTanistAVPlayer()
    let player = try avPlayer.player(url: url)

    return player
}

13:42 - Initial Test Scaffolding

import Testing
@testable import BOTanist


// When using the default init Plant(type:) make sure the planting style is graft
@Test func plantingRoses() {
    // First create the two Plant structs
    

    // Verify with #expect
}

14:36 - Complete Test

import Testing
@testable import BOTanist


// When using the default init Plant(type:) make sure the planting style is graft
@Test
func plantingRoses() {
    // First create the two Plant structs
    let plant = Plant(type: .rose)
    let expected = Plant(type: .rose, style: .graft)

    // Verify with #expect
    #expect(plant == expected)
}

17:35 - Custom Tag

extension Tag {
    @Tag static var planting: Self
}

17:42 - Tag Usage in @Test

.tags(.planting)

20:37 - Slow Asset Loading

for asset in allAssets {
    asset.load()
}

20:54 - Fast Asset Loading

await withDiscardingTaskGroup { group in
    for asset in allAssets {
        group.addTask {
            asset.load()
        }
    }
}