timer.md

Timer

Rx.Timer is unusual in that it's the only concrete Rx stream that doesn't require a task or external input. In truth, you could create your own "timer" stream by embedding a Foundation.Timer into a HotTask and having it emit events. The problem is that controlling the timer and avoiding retain cycles can be problematic. For this reason, I added this type to make it easy to create Timer streams that emit events at a specified interval.

The timer has several features:

• No need to worry about retain cycles. Rx.Timer will keep the timer alive only as long as itself is retained and the stream is active.
• Easily start, stop, and restart the timer manually by calling start(), stop() and restart().
• By default the Timer will use Foundation.Timer.scheduledTimer(...), which handles the majority needs. However, the handler that creates this can be replaced with whatever you want, allowing you to use timers on different run loops, etc.
• Standard Stream operations and processing chains inherent in Hot streams.

Examples

Some simple examples showing how a timer might be used.

let timer = Rx.Timer(interval: 1.0).start()

timer
  .count()
  .on{ print("\($0) sec") }

Simple example that will count the seconds and print them out.

let timer = Rx.Timer(interval: 1.0)

timer
  .count()
  .stride(10)
  .on{ print("\($0) sec") }

Use a Timer that emits events every second and take only the 10th second and print it out. Of course, you could just create a Timer with a 10 second interval, but I wanted to show how you might leverage an existing Timer.

let timer = Rx.Timer(interval: 1.0)

timer
  .map{ Date() }
  .on{ print($0) }

Map the timer events into a Date and print it.