Cornelius Mark

Innovative macOS/iOS developer building apps that shine. Need a bold app solution? DM me let’s create! ⬇️

[Cornelius Mark @corneliusmark]

Hello,

I craft macOS and iOS apps that scale, perform, and delight users. From modular architectures to bug-free code, I deliver solutions that grow with your vision. Let’s chat about your next project!

Here’s what clients say about my work:
⭐⭐⭐⭐⭐ "Mark is a guru in everything MacOS and app store related. A pleasure to work with!" – Safari extension for a search engine.
⭐⭐⭐⭐⭐ "Great communication, fluent English, quick action, knows exactly what he's doing." – macOS taskbar app.
⭐⭐⭐⭐⭐ "Mark was great to work with and is an expert at his craft." – WidgetKit widgets for Big Sur.

DM me let's build something amazing!

Best,
Mark

[Cornelius Mark @corneliusmark]

@enescancik Custom event tracking in code helped fill gaps when App Store Connect reports lagged.

[Cornelius Mark @corneliusmark]

@MengTo @CryptoFan1985 Profiling with Instruments showed main thread blocks that cut launch time by half after fixes.

[Cornelius Mark @corneliusmark]

@Rifat_EE @Apple On device processing reduced my API costs by 60 percent while keeping user data local.

[Cornelius Mark @corneliusmark]

@PopBase This pushes developers to match native feel instead of relying on web views which often feel slower on iOS.

[Cornelius Mark @corneliusmark]

Three client apps proved my simple test works.
I used three questions to check what users really value. Then I tracked revenue before and after.
Every app saw growth. One turned flat sales into steady income. Another doubled what it made. The third kept more users paying longer.
Six months later one founder still messages me with updates. He shares wins and asks for the next step.
If you build iOS apps and want proof before you spend months coding, this test gives it.
Comment TEST below. I will send you the three questions today.

[Cornelius Mark @corneliusmark]

Indie app makers and solo founders. Your iOS app has a hidden problem. Users download it. They try it. Then low reviews come in. One client had a budget app at 2.1 stars. We found the issue and added one micro interaction. It showed spending in a clear way right at the start. 9 days later ratings reached 4.8 stars. The part clients never see until we fix it together is this kind of detail. It turns users who leave into users who stay and rate high. If your app struggles with retention or low stars, this is likely the fix you need. Comment MICRO or DM me. I will help you find and add it.

[Cornelius Mark @corneliusmark]

@amytam01 @SpaceX @xai As AI tools get stronger, the edge for app builders may shift toward picking the right problems to solve and making the final product feel simple and dependable.

[Cornelius Mark @corneliusmark]

@PerceptronNTWK I have worked on apps where the AI part gave good answers in tests but felt off once real user data and changing conditions came in. Fresh context makes a big difference.

[Cornelius Mark @corneliusmark]

@ShadowofEzra Building apps now means learning how to direct AI output rather than writing every line. The developers who will stay busy are the ones who can turn AI drafts into reliable, reviewed products.

[Cornelius Mark @corneliusmark]

@BernieSanders For apps that help users with daily tasks using AI, the backend costs matter a lot. Any shift that makes the models more expensive changes what kinds of apps can stay free or low cost.

[Cornelius Mark @corneliusmark]

@OpenAI I tested similar AI tools on a SwiftUI prototype last month. It built the screens fast but the data sync between views needed manual fixes to feel reliable.

[Cornelius Mark @corneliusmark]

Founders building iOS apps, here is a story I keep seeing. A founder put off App Store Connect automation. He thought it could wait. Then the metadata rejections started coming. He reached number six. That added three more weeks to his review process. Even six months after launch he is still messaging me for updates. The lesson is simple. Set up your automation from day one. Your launches stay on track so you can focus on real users and growth instead of chasing reviews. What is the biggest delay you have faced with App Store submissions?

[Cornelius Mark @corneliusmark]

Comment TEST and I send you the full test plus outreach script. Know before Monday.

[Cornelius Mark @corneliusmark]

Last year we put 22 app ideas through real validation.

[Cornelius Mark @corneliusmark]

Reach out, ask three questions, and get clear answers fast.

[Cornelius Mark @corneliusmark]

@johnnybuildr Which part of the build took the longest once you had the core idea finished?