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@inket
Last active February 1, 2024 06:14
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How to take screenshots of SwiftUI previews
#if DEBUG
import SwiftUI
private let screenshotDirectory = "/Users/inket/Desktop/"
struct PreviewScreenshot: ViewModifier {
struct LocatorView: UIViewRepresentable {
let tag: Int
func makeUIView(context: Context) -> UIView {
return UIView()
}
func updateUIView(_ uiView: UIView, context: Context) {
uiView.tag = tag
}
}
@Environment(\.colorScheme) var colorScheme
private let tag = Int.random(in: 0..<Int.max)
let screenshotName: String
private var screenshotPath: String {
let colorSchemeName = colorScheme == .dark ? "dark" : "light"
let deviceName = UIDevice.current.name
let actualName = "\(screenshotName)-\(colorSchemeName).png"
return "\(screenshotDirectory)/\(deviceName)/\(actualName)"
}
private func createDirectory() {
let deviceName = UIDevice.current.name
let screenshotDir = "\(screenshotDirectory)/\(deviceName)/"
var isDir: ObjCBool = false
if !FileManager.default.fileExists(atPath: screenshotDir, isDirectory: &isDir) {
try! FileManager.default.createDirectory(
atPath: screenshotDir,
withIntermediateDirectories: true,
attributes: nil
)
} else if !isDir.boolValue {
fatalError()
}
}
func body(content: Content) -> some View {
VStack(spacing: 0) {
LocatorView(tag: tag).frame(width: 0, height: 0)
content
}
.onAppear {
DispatchQueue.main.asyncAfter(deadline: .now() + .seconds(1)) {
UIApplication.shared.windows.forEach { window in
guard window.viewWithTag(self.tag) != nil else { return }
UIGraphicsBeginImageContextWithOptions(window.bounds.size, window.isOpaque, 0.0)
window.drawHierarchy(in: window.bounds, afterScreenUpdates: true)
let image = UIGraphicsGetImageFromCurrentImageContext()!
UIGraphicsEndImageContext()
self.createDirectory()
try? image.pngData()?.write(to: URL(fileURLWithPath: self.screenshotPath))
}
}
}
}
}
extension View {
func screenshot(name: String) -> some View {
self.modifier(PreviewScreenshot(screenshotName: name))
}
}
struct PreviewScreenshot_Previews: PreviewProvider {
static var previews: some View {
// Usage:
// 1. Use .screenshot(name:) on your view
// 2. Turn on Live Preview (the play icon in the Canvas)
// => Screenshot will appear in a few seconds
Text("Screenshot!")
.screenshot(name: "Test")
.colorScheme(.dark) // colorScheme should come after .screenshot(name:) to affect the screenshot name
}
}
#endif
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