WatchdogInspector
A debugging tool that displays real-time framerate (fps) and detects main thread stalls in iOS apps via the status bar.
What is WatchdogInspector?
WatchdogInspector is an iOS debugging tool that displays the app's current framerate (fps) in the status bar and detects main thread stalls. It helps developers identify performance issues that cause UI lag by providing real-time visual feedback and optional exception throwing for blocked threads.
iOS developers and mobile engineers who need to monitor and optimize app performance, particularly those working on apps requiring smooth animations and responsive interfaces.
Developers choose WatchdogInspector for its non-intrusive, real-time performance monitoring directly in the status bar, eliminating the need for external profiling tools during development and enabling quick identification of framerate drops and main thread blocks.
Overview
Shows your current framerate (fps) in the status bar of your iOS app
Use Cases
Best For
- Debugging UI jank and animation stutters in iOS apps
- Monitoring real-time framerate during development and testing
- Identifying main thread stalls that cause app freezes
- Providing visual performance feedback without external tools
- Optimizing apps for 60 fps smooth scrolling and transitions
- Educational purposes to understand iOS performance bottlenecks
Not Ideal For
- Production apps where debugging tools must be disabled to avoid overhead or UI modifications
- Projects requiring comprehensive performance profiling beyond framerate, such as memory leaks or CPU usage
- Teams that prefer integrated Xcode tools over external dependencies for debugging
Pros & Cons
Pros
Shows current framerate in the status bar with updates every 2 seconds, providing immediate visual feedback on performance without external tools.
Throws exceptions when the main thread is blocked beyond a customizable timeout (default 3 seconds), helping quickly identify UI freezes during development.
Simple API with start() and stop() methods, and support for CocoaPods and Carthage, making setup straightforward as shown in the README examples.
Status bar changes color from green (good fps) to red (bad fps), offering an intuitive at-a-glance indicator of app performance health.
Cons
The README explicitly warns against using WatchdogInspector in production, limiting its utility to development and testing environments only.
Focuses solely on framerate and main thread stalls, lacking features for monitoring memory, CPU, battery usage, or network performance.
Modifies the status bar for debugging, which could conflict with custom UI elements or other debugging overlays in complex apps.
Frequently Asked Questions
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