I understand you are looking for someone to build an app that creates a fake notes app that can be added to a spectator's phone with NFC or an app clip to make it appear as though the notes app has been locked. Once the lock has been activated, the magician can pretend to look at the time before pressing the lock button on their phone, at which point the message that has been previously written in the fake notes app appears at the top of the screen (in small letters). This allows them to retrieve the secret information.
I have over seven years of experience in data science, specifically in artificial neural networks and deep learning, as well as in machine learning and data science more broadly. This gives me the knowledge and skills necessary to tackle this project. Moreover, my objective C skills give me the ability to understand how blockchain works and develop an application on top of it without any trouble.