The Technical Blog of Benjamin Pearson... :
"Early on I had to implement a drop down calendar with a similar look and feel as the native calendar app. There appears to be two major, actively maintained implementations on Github: Kal and Tapku Library - I went with Tapku, however Kal could possibly be just as good or even better (let me know if it is). Tapku is super easy to integrate and offers a bunch of UI components including Coverflow, Progress Bars, Graphs, and importantly in this instance - a Calendar."
Via Vincent Demay