Will having two NSTimers in one class cause them to be less accurate?

I have one NSTimer which is my main game loop, it calls 60 times a second. I have another timer which is a countdown, which gets called 0.001 times a second. Is it normal that timer is not accurate? or开发者_C百科 should i call the countdown timer fewer times per second?

NSTimers are not accurate. The time interval you specify is simply a goal. The NSTimer will try to hit that goal but the more stuff you have running on that thread the slower the cycle time will be. Your 0.001 timer is probably going way too fast to be useful and will suffer from accuracy problems. If you need real time accuracy you will have to track what time the timer is actually firing with an NSDate and compensate accordingly.

If I'm reading your question correctly the second timer (which I assume is fired every 0.001) seconds is not going to be accurate.

NSTimer has a resolution of about 50-100 milliseconds (0.05s-0.1s) and this can be significantly impacted if your run loop is loaded.