Core libraries

RestKit: It is a framework for consuming and modeling RESTful web resources on iOS and OS X.

AFNetworking： It is a delightful iOS and OSX networking framework.

MagicalRecord: Core data

InjectiveI framework.

AGi18n: It easily localizes your iOS apps by automatically extracting texts from code and XIB files into localizable strings.

SDWebImage:It is an asynchronous image downloader with cache support with an UIImageView category (for ones not satisfied with UIImageView+AFNetworking functionality).

SSKyechain:It is a simple Cocoa wrapper for the keychain that works on Mac and iOS.

LUKeychainAccess: It is a wrapper for iOS keychain services that behaves just like NSUserDefaults.

FileMD5Hash:It is a library for computing MD5 hashes of files with small memory usage.

ISO8601DataFormatter:It is a Cocoa NSFormatter subclass to convert dates to and from ISO-8601-formatted strings. It supports calendar, week, and ordinal formats.

NSData+Base64:It is Base64 for NSData.

TransitionKit:It is a block-based State Machine API for Objective-C.

NSXtensions: It is a collection of useful categories for standard Cocoa classes.

BlockKit: It is a framework that block-ifies pieces of foundation and UIKit that are in desperate need.

Libextobjc:The extended Objective-C library extends the dynamism of the Objective-C programming language to support additional patterns present in other programming languages (including those that are not necessarily object-oriented).

Debugging and logging
• TestFlightSDK: It is a TestFlight SDK for over-the-air beta testing and crash reporting.
• Reveal-iOS-SDK: See your application's view hierarchy at runtime with advanced 2D and 3D visualizations.
• PonyDebugger: It is a client library and a gateway server combination that uses chrome developer tools on your browser to debug your application's network traffic and managed object contexts.
• CocoaLumberjack: It is a fast and simple, yet powerful and flexible logging framework for Mac and iOS.
• LibComponentLogging-Core: It is a logging library that provides log levels, log components, and pluggable logging backends.
• LibComponentLogging-NSLog: The LibComponentLogging logging backend redirects logging to NSLog.
• CBIntrospect: Introspect is a tool for iOS that aids in debugging user interfaces built with UIKit. It communicates with a view introspector, a desktop app.

Kiwi: It is a Behavior-Driven Development library for iOS development.
• TKSenTestAsync: It is a SenTest category with asynchronous support.
• Expecta: It is a matcher framework for Objective-C and Cocoa.
• Nocilla: It is a stunning HTTP stubbing for iOS. Testing HTTP requests has never been easier.
• OCMock: It is an Objective-C implementation of mock objects.
• Calabash: It is an automated testing technology for Android and iOS native
and hybrid applications. The home page is available at http://calaba.sh.
• Frank: It is automated acceptance tests for native iOS apps. The home page
is available at http://www.testingwithfrank.com. User interface
• UI7Kit: It is a GUI toolkit to implement iOS7 look-and-feel UIKit under iOS5/iOS6. It is also supported for patching UIKit to UI7Kit in runtime.
• SVProgressHUD: It is a clean and lightweight progress HUD for your iOS app.
• SIAlertView: It is a UIAlertView replacement with block syntax and fancy
transition styles.
• PSTCollectionView: It is open source and a 100 percent API-compatible replacement of UICollectionView for iOS4+.
• QuickDialog: It is a quick and easy dialog screen for iOS.
• ISRefreshControl: It is an iOS4-compatible UIRefreshControl.
• ViewDeck: It is an implementation of the sliding functionality found in the Path 2.0 or Facebook iOS apps.
• BCGenieEffect: It is an OSX-style genie effect inside your iOS app.
• JSMessagesViewController: It is a message's UI for iPhone and iPad.
• CorePlot: It is a Cocoa plotting framework for Mac OS X and iOS.
• DDPageControl: It is an easily customizable alternative to UIKit's UIPageControl.
• MTStatusBarOverlay: It is a custom iOS status bar overlay seen in apps, such as Reeder, Evernote, and Google Mobile App.
• FontasticIcons: It is an Objective-C wrapper for iconic fonts. [ 99 ]

Other
• ZBarSDK: It is a QR and barcode scan library
• ObjQREncoder: It is an Objective-C QR encoder
• CardIO: It is an easy-to-use credit card scanning tool
• CHCSVParser: It is a proper CSV parser for Objective-C