What it is
Smith lets users record patterns of knocks, which are tied to several functions in iOS, such as calling someone, or running a workflow. After these patterns of knocks are recorded, the app has a listening mode that listens for vibrations on the surface that it is on. If a user knocks on the table in one of the specified patterns, the function in run in the form of URL Schemes that are built into iOS.
Challenges I ran into
Getting Core Data to work properly
Detecting knocks with accelerometer
Recognizing Patterns of knocks
*Agent Smith picture taken from facets.la