Language Build Status Platform support CocoaPods Compatible Carthage compatible License MIT

Class for logging excessive blocking on the main thread. It watches the main thread and checks if it doesn’t get blocked for more than defined threshold.

? Main thread was blocked for 1.25s ?

You can also inspect which part of your code is blocking the main thread.


Simply, just instantiate Watchdog with number of seconds that must pass to consider the main thread blocked. Additionally you can enable strictMode that stops the execution whenever the threshold is reached. This way, you can inspect which part of your code is blocking the main thread.

let watchdog = Watchdog(threshold: 0.4, strictMode: true)

Don’t forget to retain Watchdog somewhere or it will get released when it goes out of scope.


  • iOS 8.0+, tvOS 9.0+ or macOS 10.9+
  • Swift 5.0



Add the following to your Cartfile:

github "wojteklu/Watchdog"

Then run carthage update.

Follow the current instructions in Carthage’s README for up to date installation instructions.


Add the following to your Podfile:

pod 'Watchdog'

You will also need to make sure you’re opting into using frameworks:



Manually add the file into your Xcode project. Slightly simpler, but updates are also manual.


Wojtek Lukaszuk @wojteklu


Watchdog is available under the MIT license. See the LICENSE file for more info.