What is the fastest I should run an NSTimer?

What is the fastest I can run an NSTimer and still get rel开发者_运维知识库iable results? I've read that approaching 30ms it STARTS to become useless, so where does it "start to start becoming useless"...40ms? 50ms?

Say the docs:

the effective resolution of the time interval for a timer is limited to on the order of 50-100 milliseconds

Sounds like if you want to be safe, you shouldn't use timers below 0.1 sec. But why not try it in your own app and see how low you can go?

You won't find a guarantee on this. NSTimers are opportunistic by nature since they run with the event loop, and their effective finest granularity will depend on everything else going on in your app in addition to the limits of whatever the Cocoa timer dispatch mechanisms are.

What's you definition of reliable? A 16 mS error in a 1 second timer is under 2% error, but in a 30 mS timer is over 50% error.

NSTimers will wait for whatever is happening in the current run loop to finish, and any errors in time can accumulate. e.g. if you touch the display N times, all subsequent repeating NSTimer firings may be late by the cumulative time taken by 0 to N touch handlers (plus anything else that was running at the "wrong" time). etc.

CADisplayLink timers will attempt to quantize time to the frame rate, assuming that no set of foreground tasks takes as long as a frame time.

Depends on what kind of results you are trying to accomplish. NSTimer Class 0.5 - 1.0 is a good place to start for reliable results.