-
InfluxDB
Power Real-Time Data Analytics at Scale. Get real-time insights from all types of time series data with InfluxDB. Ingest, query, and analyze billions of data points in real-time with unbounded cardinality.
iOS programming is really straightforward, and with the advent of Swift and SwiftUI, it is really accessible. I kicked around an idea last year, and managed to get quite a decent prototype together very quickly. It doesn't have the best documentation for the language and software development kits, but there are loads of resources on the internet (Hacking with Swift is a good place to start).
NOTE:
The number of mentions on this list indicates mentions on common posts plus user suggested alternatives.
Hence, a higher number means a more popular project.