如何将TimeInterval设置为每秒512？

Question

I am working on graph using opengl, I want to set timer for 512 values per second I did like this:

self.animationTimer = [NSTimer scheduledTimerWithTimeInterval:1.0/512.0 
                               target:self
                               selector:@selector(drawView) 
                               userInfo:nil 
                               repeats:YES];

In draw method, I have plotted graph but it is not printing 512 values per second.

Can any one please help me, whether it is right or wrong?

Answer 1

An NSTimer probably just can't fire that fast.

A timer is not a real-time mechanism; it fires only when one of the run loop modes to which the timer has been added is running and able to check if the timer's firing time has passed. Because of the various input sources a typical run loop manages, the effective resolution of the time interval for a timer is limited to on the order of 50-100 milliseconds.

http://developer.apple.com/library/ios/#documentation/cocoa/reference/Foundation/Classes/NSTimer_Class/Reference/NSTimer.html

Which gives you 10-20 ticks a second, unless you're doing something really special.

Answer 2

That's just not going to work.

There are (at least) two reasons.

1. " Because of the various input sources a typical run loop manages, the effective resolution of the time interval for a timer is limited to on the order of 50-100 milliseconds ." So you can't expect to have more than around ten timers fire per second.
2. Not sure what the maximum framerate on iOS is, but there's probably not much point in going much above 60.

Answer 3

[NSTimer scheduledTimerWithTimeInterval:1.0f/512.0f target:self selector:@selector(drawView) userInfo:nil repeats:YES];

try to use this one

let me know whether it is working or not!!!

Happy Coding!!!!

Answer 4

I am able to plot 512 values per second.. same timeinterval i used but i refer Accelerometer graph: http://developer.apple.com/library/ios/#samplecode/AccelerometerGraph/Listings/MainViewController_m.html#//apple_ref/doc/uid/DTS40007410-MainViewController_m-DontLinkElementID_10 I customized it according to my requirement and it working as i fine. Thanks!!!