PonyDebugger

PonyDebugger is a remote debugging toolset. It is a client library and gateway server combination that uses Chrome Developer Tools on your browser to debug your application's network traffic and managed object contexts.

To use PonyDebugger, you must implement the client in your application and connect it to the gateway server. There is currently an iOS client and the gateway server.

PonyDebugger is licensed under the Apache Licence, Version 2.0 (http://www.apache.org/licenses/LICENSE-2.0.html).

Changes

v0.2.1-beta1 - 2013-01-12

• Bonjour support (Thanks @jeanregisser!)
• Memory leak fix (Thanks @rwickliffe!)

Features

Network Traffic Debugging

PonyDebugger sends your application's network traffic through ponyd, PonyDebugger's proxy server. You use Inspector's Network tools to debug network traffic like how you would debug network traffic on a website in Google Chrome.

PonyDebugger forwards network traffic, and does not sniff network traffic. This means that traffic sent over a secure protocol (https) is debuggable.

Currently, the iOS client automatically proxies data that is sent via NSURLConnection. This means that it will automatically work with AFNetworking, and other libraries that use NSURLConnection for network requests.

Core Data Browser

The Core Data browsing feature allows you to register your applcation's NSManagedObjectContexts and browse all of its entities and managed objects. You browse data from the IndexedDB section in the Resource tab in Chrome Developer Tools.

These are read-only stores at the moment. There are plans to implement data mutation in a future release.

View Hierarchy Debugging

PonyDebugger displays your application's view hierarchy in the Elements tab of the Chrome Developer Tools. As you move through the XML tree, the corresponding views are highlighted in your app. You can edit the displayed attributes (i.e. frame, alpha, ...) straight from the Elements tab, and you can change which attributes to display by giving PonyDebugger an array of UIView key paths. Deleting a node in the elements panel will remove that node from the view hierarchy. Finally, when a view is highlighted, you can move it or resize it from the app using pan and pinch gestures.

An "inspect" mode can be entered by clicking on the magnifying glass in the lower left corner of the Developer Tools window. In this mode, tapping on a view in the iOS app will select the corresponding node in the elements panel. You can also hold and drag your finger around to see the different views highlighted. When you lift your finger, the highlighted view will be selected in the elements panel.

Currently only a subset of the actions possible from the elements panel have been implemented. There is significant room for continued work and improvement, but the current functionality should prove useful nonetheless.

Quick Start

Prerequisite: Xcode's Command Line Tools must be installed from the "Downloads" preference pane.

curl -sk https://cloud.github.com/downloads/square/PonyDebugger/bootstrap-ponyd.py | \
  python - --ponyd-symlink=/usr/local/bin/ponyd ~/Library/PonyDebugger

This will install ponyd script to ~/Library/PonyDebugger/bin/ponyd and attempt to symlink /usr/local/bin/ponyd to it. It will also download the latest chrome dev tools source.

Then start the PonyDebugger gateway server

ponyd serve --listen-interface=127.0.0.1

In your browser, navigate to http://localhost:9000. You should see the PonyGateway lobby. Now you need to integrate the client to your application.

For more detailed instructions, check out the gateway server README_ponyd.

PonyDebugger iOS Client

The PonyDebugger iOS client lets you to debug your application's network requests and track your managed object contexts.

Technical

• Requires iOS 5.0 or above
• Uses ARC (Automatic Reference Counting).
• Uses SocketRocket as a WebSocket client.

Installing

• Extract a tarball or zipball of the repository into your project directory. If you prefer, you may also add the project as a submodule. The iOS client uses SocketRocket as a dependency, and it is included as a submodule.

cd /path/to/YourApplication
mkdir Frameworks
git submodule add git://github.com/square/PonyDebugger.git Frameworks/PonyDebugger
git submodule update --init --recursive

• Add PonyDebugger/PonyDebugger.xcodeproj as a subproject.

• In your Project Settings, add the PonyDebugger target as a Target Dependency in the Build Phases tab.

• Link libPonyDebugger.a, libSocketRocket.a, and the Framework dependencies to your project.

• PonyDebugger and SocketRocket take advantage of Objective C's ability to add categories on an object, but this isn't enabled for static libraries by default. To enable this, add the -ObjC flag to the "Other Linker Flags" build setting.

Framework Dependencies

Your .app must be linked against the following frameworks/dylibs in addition to libPonyDebugger.a and libSocketRocket.a.

• libicucore.dylib
• CFNetwork.framework
• CoreData.framework
• Security.framework
• Foundation.framework

Usage

PonyDebugger's main entry points exist in the PDDebugger singleton.

PDDebugger *debugger = [PDDebugger defaultInstance];

To connect automatically to the PonyGateway on your LAN (via Bonjour):

[debugger autoConnect];

Or to open the connection to a specific host, for instance ws://localhost:9000/device:

[debugger connectToURL:[NSURL URLWithString:@"ws://localhost:9000/device"]];

To manually close the connection:

[debugger disconnect];

Network Traffic Debugging

To enable network debugging:

[debugger enableNetworkTrafficDebugging];

PonyDebugger inspects network data by injecting logic into NSURLConnectionDelegate classes. If you want PonyDebugger to automatically find these classes for you:

[debugger forwardAllNetworkTraffic];

This will swizzle methods from private APIs, so you should ensure that this only gets invoked in debug builds. To manually specify delegate classes:

[debugger forwardNetworkTrafficFromDelegateClass:[MyClass class]];

These methods should be invoked before the connection is opened.

Core Data Browser

PonyDebugger also allows you to browse your application's managed objects. First, enable Core Data debugging:

[debugger enableCoreDataDebugging];

To register a managed object context:

[debugger addManagedObjectContext:self.managedObjectContext withName:@"My MOC"];

View Hierarchy Debugging

To enable view hierarchy debugging:

[debugger enableViewHierarchyDebugging];

PonyDebugger will inject logic into UIView add/remove methods to monitor changes in the view hierarchy.

You can also set the attributes you want to see in the elements panel by passing an array of UIView key path strings

[debugger setDisplayedViewAttributeKeyPaths:@[@"frame", @"hidden", @"alpha", @"opaque"]];

PonyDebugger uses KVO to monitor changes in the attributes of all views in the hierarchy, so the information in the elements panel stays fresh.

The repository contains a test application to demonstrate PonyDebugger's capabilities and usage.

Known Issues / Improvements

• CoreData.framework must be linked, even if you do not use the Core Data browsing functionality.

• iOS 5.1 and below: In certain cases, -[NSURLConnectionDataDelegate connection:willSendRequest:redirectResponse:] will never get called. PonyDebugger requires this call to know when the request was sent, and will warn you with a workaround that the timestamp is inaccurate.

  To fix the timestamp, make sure that Accept-Encoding HTTP header in your NSURLRequest is not set (by default, iOS will set it to gzip, deflate, which is usually adequate.

  AFNetworking users: if you subclass AFHTTPClient, call [self setDefaultHeader:@"Accept-Encoding" value:nil];.

Contributing

Any contributors to the master PonyDebugger repository must sign the Individual Contributor License Agreement (CLA). It's a short form that covers our bases and makes sure you're eligible to contribute.

When you have a change you'd like to see in the master repository, send a pull request. Before we merge your request, we'll make sure you're in the list of people who have signed a CLA.

Some useful links:

• Chrome Remote Debugging Documentation
• WebKit Inspector Protocol Definition on GitHub