Around 3 weeks ago, I came across a reddit post from someone who was looking to see if anyone was interested in taking over a 12-14 year old objective c app which hadn't been on the app store for many years. I responded and decided to do it.<p>The app is called Painteresque. It lets you turn photos to charcoal drawings, paintings etc while doing all the processing locally on device:<p><a href="https://apps.apple.com/ca/app/painteresque-photo-to-sketch/id6742038583">https://apps.apple.com/ca/app/painteresque-photo-to-sketch/i...</a><p>The app is entirely free to use, has no ads, third party analytics, trackers, subscriptions or other junk. It does offer 5 options for tips (which are basically consumable in app purchases), portion of which I will share with the original developer. However, based on my past experiences with tips, they are rarely given by users.<p>Here's a screenshot of the OLD app:<p><a href="https://i.imgur.com/fPhoqlp.jpeg" rel="nofollow">https://i.imgur.com/fPhoqlp.jpeg</a><p>The old app was built like 12-14 years ago in a combination of objective c and vanilla C. The "filters" were built in C while the UI was in objective c.<p>The codebase was so old that it wasn't even using ARC (Automatic Reference Counting).<p>The app would also instantly crash because back in those days, using the camera or adding photos to photo library didn't require declaring permission things like `NSCameraUsageDescription`, `NSLocationWhenInUseUsageDescription`.<p>Also had to remove obsolete frameworks to get it to run on devices iOS 12 onwards.<p>It was also not built for retina displays, nor handling safe area layout guides.<p>After fixing all these things, I got the old app to work on phone. But the UI was very rough and rudimentary. Back in those days, it would get approved by Apple. But nowadays, Apple is very strict about these things.<p>So, I decided to rebuild the app from scratch in Swift with, what I think, is a better UI design. I still used the old vanilla C code for the filters with some small changes and extra filters of my own. But the rest of the UI is all from scratch. I also incorporated things like `NSOperationQueue` for background processing of the image filtration as it can take a few seconds to generate. I incorporated caching of the images, preview thumbnails etc. to disk because the current phones have cameras which take humongous photos that can use a lot of ram if kept in memory.<p>The only package dependency the app uses is SnapKit to make auto layout simpler. The UI is made with code instead of storyboards.<p>The App Store screenshots are all made by me from scratch using Photopea, a browser alternative to Photoshop. The app icon is still the old icon, except I changed the background to be an off-white color instead of the old blue color to make it look a bit more modern.<p>Overall, this process took about 3 weeks. Most of the important work was done in about 1.5-2 weeks. The rest of the time was spent adding things like tipping in app purchases, UI improvements, tweaking the filters, adding feedback button etc.<p>The App Store review was fast. I submitted at 6:30 PM and it was approved at 4 AM. Also got an update approved last night to fix some slowness issue when opening new images.<p>The new app on iOS is only around 1.8 MB, most of it used by images for the buttons and app icon.<p>Ask me anything you'd like about this experience. Have any of you taken over an old app and rebuilt it?