View to UIImage - Swift code

View+Screenshot.swift

import SwiftUI

extension View {
    @MainActor public func screenshot(scale: CGFloat = 1.0) -> UIImage? {
        if #available(iOS 16.0, *) {
            // ImageRendererの方が処理速度が早く、画像が高精細
            let renderer = ImageRenderer(content: self)
            renderer.scale = scale
            renderer.isOpaque = true
            return renderer.uiImage
        } else {
            let controller = UIHostingController(rootView: self)
            let view = controller.view!

            let bounds = CGRect(origin: .init(x: .zero, y: adjustY()), size: view.intrinsicContentSize)
            view.bounds = bounds
            view.backgroundColor = .clear

            let format = UIGraphicsImageRendererFormat(for: .init(displayScale: scale))
            let image = UIGraphicsImageRenderer(bounds: bounds, format: format).image { _ in
                view.drawHierarchy(in: bounds, afterScreenUpdates: true)
            }
            return image
        }
    }

    /// UIGraphicsImageRendererで画像描画時に発生するY座標軸上のズレを調整するためのポイント
    ///
    /// ポートレート時のみズレる
    private func adjustY() -> CGFloat {
        switch UIScreen.main.nativeBounds.height {
        case 1_136: // 4.0 inch
            return 10
        case 1_334: // 4.7 inch
            return 10
        case 2_340: // 5.4 inch
            return 25
        case 2_208: // 5.5 inch
            return 10
        case 2_436: // 5.8 inch
            return 22
        case 1_792: // 6.1 inch
            return 24
        case 2_532: // 6.1 inch
            return 71 / 3 // 23.666666666666667
        case 2_688: // 6.5 inch
            return 22
        case 2_778: // 6.7 inch
            return 71 / 3 // 23.666666666666667
        default:
            return .zero
        }
    }
}