Please help me contribute to this list, for non-experience iOS developers or someone who need a come-in-handy library list to refer or to use in their projects. Fork, edit and send a PR are all things you can do!

Table of Contents

• UI Component
  • Collection
  • Menu
  • Button
  • Chart
  • Tabbar
  • HUD
  • Font
• Multimedia
  • Audio
  • Video
  • Image
• Networking
  • Network
  • Downloader
• Cache Technique
• Database
• Social Sharing
• PDF
• Drawing
• Development Tool
• Completed Product

All libraries are ordered randomly.

UI Component

Collection

• tapkulibrary. TapkuLibrary is an iOS library built on Cocoa and UIKit intended for broad use in applications. Support many customized UI Components.

Menu

• REMenu. Dropdown menu inspired by Vine.
• StackMenu. Stack menu looks like Dock bar in Mac OS X.
• AwesomeMenu. AwesomeMenu is a menu with the same look as the story menu of Path.
• JASidePanels. Reveal side ViewControllers similar to Facebook/Path's menu.
• RESideMenu. iOS 7 style side menu with parallax effect.

Button

Chart

• PNChart. A simple and beautiful chart lib used in Piner for iOS. Support bar chart, circle chart, line chart.
• iOSPlot. A chart library for pie chart, line chart.
• XYPieChart. A simple and animated Pie Chart for your iOS app.
• HUChart. A simple (but the first) semi circle chart (half pie chart) for iOS.
• JYRadarChart. A library for radar chart.
• TEAChart. A simple and intuitive iOS chart library, includes Contribution graph (like of github), clock chart, and bar chart.

Tabbar

• TabBarKit. A flexible Tab Bar implementation for iPhone and iPad.
• AKTabBarController. Adaptative and customizable tab bar for iOS.

HUD

• MBProgressHUD. MBProgressHUD is an iOS drop-in class that displays a translucent HUD with an indicator and/or labels while work is being done in a background thread.
• SVProgressHUD. A clean and lightweight progress HUD for iOS app. SVProgressHUD is an easy-to-use HUD meant to display the progress of an ongoing task.
• MBAlertView. A fast block-based alert and HUD library with a simple API.
• SDCAlertView. SDCAlertView is intended as a pixel-for-pixel UIAlertView.

Font

• FBDigitalFont. This library includes some kind of digital fonts. It is not TTF or OTF , just draw by CoreGraphics. Really awesome!
• ios-fontawesome. Font awesome is an iconic font for iOS.

Multimedia

Audio

• TheAmazingAudioEngine. Core Audio, Cordially: A sophisticated framework for iOS audio applications, built so you don't have to.
• SoundManager. Simple sound and music player class for playing audio on Mac and iPhone.

Video

• GPUImage. An open source iOS framework for GPU-based image and video processing.
• LBYouTubeView. A MPMoviePlayerViewController subclass that can display YouTube videos.
• VideoPlayerKit. A full video player, sharing integrated.

Image

• GPUImage. An open source iOS framework for GPU-based image and video processing.
• CLImageEditor . A code for using some image processing tasks for Image, such as crop, rotate, adjustment, Tone Curve, ...
• iCarousel. A simple, highly customisable, data-driven 3D carousel for iOS and Mac OS.
• SDWebImage. Asynchronous image downloader with cache support with an UIImageView category.

Networking

Network

• AFNetworking. A delightful iOS and OS X networking framework.
• RestKit. RestKit is a modern Objective-C framework for implementing RESTful web services clients on iOS and Mac OS X. It provides a powerful object mapping engine that seamlessly integrates with Core Data and a simple set of networking primitives for mapping HTTP requests and responses built on top of AFNetworking.

Downloader

• TCBlobDownload. Competitive big files downloads in Cocoa. Tested with files from approx 150MB to approx 1.2GB, mostly videos.
• SDWebImage. Asynchronous image downloader with cache support with an UIImageView category.

Cache Technique

• FastImageCache. iOS library for quickly displaying images while scrolling.
• SDURLCache. URLCache subclass with on-disk cache support on iPhone/iPad.
• TMCache. Fast parallel object cache for iOS and OS X. TMCache is a key/value store designed for persisting temporary objects that are expensive to reproduce, such as downloaded data or the results of slow processing.
• MKNetworkKit. Networking Framework with built in authentication and HTTP 1.1 caching standards support for iOS 5+ devices.

Database

• fmdb. A Cocoa / Objective-C wrapper around SQLite.

Social Sharing

• ShareKit. Drop in sharing features for all iPhone and iPad apps. Support Facebook, Twitter, Delicious, Email, Google Reader,Instapaper, Pinboard, Read It Later, Tumblr.
• CFShareCircle. CFShareCircle is a user interface component for iOS that can be integrated into an app as a sharing mechanism for any kind of content.

PDF

• ThatPDF. ThatPDF is an open source application for reading and annotating pdfs.
• PDFKitten. A framework for extracting data from PDFs in iOS. Support search, highlight PDF.
• Viewer. PDF Viewer Library for iOS.
• Reader. PDF Reader Core for iOS.
• FastPdfKit. A Static Library to be embedded on iOS applications to display pdf documents. It's a powerful framework for showing PDF, but it's just a framework, not open all source.

Drawing

• Inkpad. Vector illustration app for the iPad. It supports paths, compound paths, text, images, groups, masks, gradient fills, and an unlimited number of layers.
• Brushes. Painting app for the iPhone and iPad.

Development Tool

• VVDocumenter-Xcode. Xcode plug-in which helps you write Javadoc style documents easier. Just type /// and write documented comment. Support XCode 4 & Xcode 5.
• UALogger. A powerful and flexible logging utility for Mac/iOS apps. Help show log better.

Completed Product

• cheddar-ios. Cheddar for iOS is the universal iPhone and iPad application for Cheddar, a simple & instant task manager.
• Inkpad. Vector illustration app for the iPad. It supports paths, compound paths, text, images, groups, masks, gradient fills, and an unlimited number of layers.
• Brushes. Painting app for the iPhone and iPad.