Here, we have identified some tools which help you to understand better what’s going on, maybe to fix bugs or to improve performance.
Cocoa Lumberjack
Cocoa Lumberjack offers advanced logging behaviors such as logging to rotated files, logging to the network, and filtering based on log level (info, debug, warn, error).
DCIntrospect
Introspect is a small set of tools for iOS that aid in debugging user interfaces built with UIKit. It's especially useful for UI layouts that are dynamically created or can change during runtime, or for tuning performance by finding non-opaque views or views that are re-drawing unnecessarily. It's designed for use in the iPhone simulator, but can also be used on a device.
Pony Debugger
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.
Runscope
Runscope is a service running online that can capture requests, log details, and give you valuable data about your API.
SimPholders
Quick, easy access to your simulator folders. Browse by iOS version, then app name and jump right to the folder in Finder.
Spark Inspector
The Spark Inspector integrates directly into Xcode, so you don't need to add frameworks or modify your project to inspect your app in the iOS Simulator. The Spark Inspector also includes a framework you can add to your app. This allows you to inspect apps running on devices, start NSNotification monitoring at app launch, and integrate the Spark Inspector into a build configuration.