Hello,

my first project is a camera, taking pictures and saving these into the camera roll, which works as expected. Now I am trying to add a custom watermark as text to every picture before saving.

I found the example Project 27 (mouse and text). The idea is to use the camera picture instead of the mouse, add the text and save it:

func drawImagesAndText(_ photo: AVCapturePhoto) -> UIImage {
    // 1
    let renderer = UIGraphicsImageRenderer(size: CGSize(width: 512, height: 512))
    // let renderer = UIGraphicsImageRenderer(size: CGSize(width: photo.size.width, height: photo.size.height))

    let img = renderer.image { ctx in
        // 2
        let paragraphStyle = NSMutableParagraphStyle()
        paragraphStyle.alignment = .center

        // 3
        let attrs: [NSAttributedString.Key: Any] = [
            .font: UIFont.systemFont(ofSize: 36),
            .paragraphStyle: paragraphStyle
        ]

        // 4
        let string = "The best-laid schemes o'\nmice an' men gang aft agley"
        let attributedString = NSAttributedString(string: string, attributes: attrs)

        // 5
        attributedString.draw(with: CGRect(x: 32, y: 32, width: 448, height: 448), options: .usesLineFragmentOrigin, context: nil)

        // 5
        // let mouse = UIImage(named: "mouse")
        guard let mouse = UIImage(data: photo.fileDataRepresentation()!) else {
            print("Unable to generate UIImage from image data.");
            // self.lastPhoto = nil;
            return
        }
        mouse.draw(at: CGPoint(x: 0, y: 0))
    }

    // 6
    return img
}

func photoOutput(_ output: AVCapturePhotoOutput, didFinishProcessingPhoto photo: AVCapturePhoto, error: Error?) {

    DispatchQueue.main.async {
        self.photoProcessingHandler(false)
    }

    if let error = error {
        print("Error capturing photo: \(error)")
    } else {
        // photoData = photo.fileDataRepresentation()
        photoData = drawImagesAndText(photo).pngData()

    }
}

My source code has two main issues:

1. I can not find the size of the AVCapturePhoto, thus a fixed size is used (line 3+4). Creating the UIImage at the beginning of the function results in memory exceeded. How can I access the size of the AVCapturePhoto?

2. Variable photoData (line 48,49) has the type Data?. According to the documentation, photo.fileDataRepresentation() can represent different types like HEIF. But UIImage does only offer jpg or png, how can I convert it back to the new image format?

Am I trying it completely wrong? Do I using the wrong frameworks and should I use AVCamFilter instead?

I would be very grateful, if I somebody has a hint so I can fix the code and complete my project.

Best regards Tobias