iPhone Push Notifications Secrets

There's no secret we have been waiting for it for a long time. After almost one year in waiting - Push notifications were annouced by Apple almost one year ago, as its answer to background-runnind apps - and after continuous delays, we finally got push notifications working with the latest iPhone OS 3.0 firmware update.


What are Push notifications and how they work?


Instead of allowing background-running apps, which would have a negative impact on performance and battery life, Push notifications allow any App to be notified of incoming messages even when not running.

Why should you keep an instant messaging app running in the background, wasting CPU cycles and memory, just to handle an hypothetical incoming message that may never come?
Wouldn't it make more sense to run the App only when and if you really got a message?

That's the principle behind push notifications, and it works rather well for most scenarios.

Of course you don't need to use it only with instant messaging apps, there are a lot of Apps out there that are starting to use Push notifications: from games challenging your friends, to chat programs, to geolocation apps that let your friends know where you are.

All without requiring your friends to have the same apps running at the same time...


Settings

Besides being able to enable/disable these push notification, you can easily adjust its settings individually for each App.

You can specify if you want Push notifications to show as Alerts (with SMS-like popup messages), with or without sound (each App can have a distinct sound) or as "badge" (showing next to the App icon.)

This means you won't have to be constantly annoyed by incoming push notifications for heavy usage Apps: just disable the sounds and alerts, and you'll have only the badge updating quietly.


The Tests

So, let's see how these push notifications work in the real word.
For the most part, they're instantaneous.

As long as you're connected to your cellular network, push works instantly.

But, how does it work when you're away from cell coverage and relying only on WiFi connection?
The issue being, the "sleep" mode of the iPhone that turns off WiFi after beeing "asleep" for a while, to save energy; how will that affect the push notifications?

If you have your iPhone working, using only WiFi Push notifications are still received instantly.

If you have it locked and "asleep" your iPhone will only check for push notifications every 15 minutes. (Which is quite reasonable.)
If meanwhile you happen to actively wake up and connect your iPhone to the WiFi network, you'll receive the push notification right away.


Conclusion

Though they might not be suitable for some specific cases, push really works well for most scenarios, and has the advantage of not sacrificing too much battery life nor requiring background-running Apps.

As you can easily tweak its settings on a App by App basis, the only thing missing is how to easily handle multiple overlapping incoming push notifications. It would be nice to have a way to see a list of the last received notifications, instead of seeing just the last one (and possibly missing a more important one that was received before.)

I hope Apple fixes that in an upcoming update.