A framerate meter that clicks like a Geiger counter when your animation drops a frame
Objective-C Ruby
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KMCGeigerCounter is a framerate meter that clicks like a Geiger counter when your animation drops a frame.

A Geiger counter detects invisible radiation particles and alerts you to what you can't see. Dropped frames aren't invisible, but it can be hard to tell the difference between 55 and 60 fps. KMCGeigerCounter makes those five dropped frames obvious.

  • If you're not consistently animating smoothly, you'll hear a rough, staticky noise.
  • If your app runs at a smooth 60 fps, you'll hear the occasional drops to 59 and 58.
  • You can even hear dropped frames from CPU spikes, like when custom table view cells enter the screen and require layout.

The onscreen framerate meter shows two numbers:

  • The number of frames dropped in the past second
  • The number of frames drawn in the past second

The meter is orange when you've dropped at least three frames in the past second.


pod 'KMCGeigerCounter'

Or copy these files into your project:

  • KMCGeigerCounter.h
  • KMCGeigerCounter.m
  • KMCGeigerCounter.aiff

If you're not using CocoaPods, you may need to add these frameworks to your Link Binary With Libraries build phase:

  • QuartzCore.framework
  • AudioToolbox.framework
  • SpriteKit.framework


In your UIApplicationDelegate, enable the tool:

- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions
    // …
    [self.window makeKeyAndVisible];

    [KMCGeigerCounter sharedGeigerCounter].enabled = YES;

Then, build and run your app. Navigate through your app and listen for clicks.

Known issue

If you use view controller based status bar style, your -preferredStatusBarStyle will be ignored, because UIKit asks the meter window for that instead of your main window. I could avoid this by giving the meter window a root view controller, but then that would affect navigation bar height. I'd appreciate any ideas about this.

Doesn't adding a view to my app slow it down?

Maybe. If the meter view causes frames to drop, the app's performance was probably toeing the line too closely in the first place.

Dumb things you probably thought of, but seriously

Remember to turn off Silent mode, or you won't hear anything.

You should remove KMCGeigerCounter before shipping to the App Store. It can't be good for battery life.

The iOS Simulator doesn't simulate device performance, so consider enabling the tool only for device builds:

[KMCGeigerCounter sharedGeigerCounter].enabled = YES;