Swift PNG Image being saved with incorrect orientation

If you need to save your PNG with correct rotation you will need to redraw your image if its orientation it is not .up. You can redraw it as follow:

extension UIImage {
    func png(isOpaque: Bool = true) -> Data? { flattened(isOpaque: isOpaque)?.pngData() }
    func flattened(isOpaque: Bool = true) -> UIImage? {
        if imageOrientation == .up { return self }
        UIGraphicsBeginImageContextWithOptions(size, isOpaque, scale)
        defer { UIGraphicsEndImageContext() }
        draw(in: CGRect(origin: .zero, size: size))
        return UIGraphicsGetImageFromCurrentImageContext()
    }
}

edit/update:

For iOS10+ tvOS10+ you can use UIGraphicsImageRenderer:

extension UIImage {
    func png(isOpaque: Bool = true) -> Data? { flattened(isOpaque: isOpaque).pngData() }
    func flattened(isOpaque: Bool = true) -> UIImage {
        if imageOrientation == .up { return self }
        let format = imageRendererFormat
        format.opaque = isOpaque
        return UIGraphicsImageRenderer(size: size, format: format).image { _ in draw(at: .zero) }
    }
}

---

Playground testing:

Usage for images without transparency:

let image = UIImage(data: try! Data(contentsOf: URL(string: "https://i.stack.imgur.com/varL9.jpg")!))!

if let data = image.png() {
    let imageFromPNGData = UIImage(data: data)
}

---

With transparency :

if let data = image.png(isOpaque: false) {
    let imageFromPNGData = UIImage(data: data)
}