Converting UIView to UIImage crashes for large views

Question

I have an app where I convert variable sized UIView to UIImage.

Problem is that when UIView becomes too large, UIGraphicsGetImageFromCurrentImageContext crashes. Logs show root cause is OS running out of memory.

This is my code:

public extension UIView {

    func snapshotImage(rectangle: CGRect) -> UIImage? {
        var image: UIImage?
        autoreleasepool { () -> () in
            UIGraphicsBeginImageContextWithOptions(rectangle.size, isOpaque, 0.0)
            defer { UIGraphicsEndImageContext() }
            if let context = UIGraphicsGetCurrentContext() {
                context.translateBy(x: -rectangle.origin.x, y: -rectangle.origin.y)
                layer.render(in: context)
                image = UIGraphicsGetImageFromCurrentImageContext()
            }
        }
        return image
    }    
}

I tried using UIGraphicsImageRenderer, something like:

extension UIView {
    func asImage() -> UIImage {
        let renderer = UIGraphicsImageRenderer(bounds: bounds)
        return renderer.image { rendererContext in
            layer.render(in: rendererContext.cgContext)
        }
    }
}

When using UIGraphicsImageRenderer app does not crash, but it fails to create resulting image, so the result is unusable.

Any idea on how to solve converting large UIViews to UIImages properly?

@canister_exister Thanks for replying. Can you be more specific, maybe some link? — paic, Dec 04 '19 at 17:40
Have you tried breaking the `UIView` into pieces, creating an image for each, and then joining the final output? — CodeBender, Dec 04 '19 at 19:08
@DonMag App starts crashing when my UIView crosses 15000 x 1800 in size. — paic, Dec 04 '19 at 19:42
@CodeBender I was thinking of something like that, but how can I join the final output without using the UIGraphicsGetImageFromCurrentImageContext again? — paic, Dec 04 '19 at 19:44
@paic It is possible to join images using OpenCV. If you are new to it, there are multiple tutorials and you can create a simple CLI to test it out before going through the effort to pull it into your app. — CodeBender, Dec 04 '19 at 20:34

Converting UIView to UIImage crashes for large views

0 Answers0