This is a simple and silly UIKit-based iOS app that demonstrates how you might render a view of an external, asynchronous data stream.
EmojiTracker uses cutting-edge sensors to track nearby emoji matching a client-specified list. It can only track one emoji at a time, but it may decide to track a different emoji at any time. It sends position updates for the currently-tracked emoji at irregular intervals to its delegate, via the EmojiTrackerDelegate protocol.
Initially, EmojiTracker doesn't know which one of the specified emoji it is tracking, but it is able to identify it via computationally-expensive and patented algorithms. A client may request identification of the currently-tracked emoji by calling EmojiTracker's identifyCurrentTarget(callback:) method. A callback is used because the identification takes an unpredictably lengthy amount of time.
LunchTracker uses EmojiTracker to plot the location of nearby lunch-item emoji, and provides a button to initiate emoji identification. Remember, EmojiTracker may decide to track another emoji at any time, so initiate identification frequently!