If you are a founder trying to create a new mobile app or an investor trying decide whether an app has enduring value, it is helpful to separate the ways that people use apps into four categories.

LIExposeController is a new navigation paradigm for iOS apps. A great example is LinkedIn's iPhone app. LIExposeController acts as a container view controller, much like UINavigationController or UITabBarController. It manages a set of UIViewControllers as separate "stacks" so that users can easily switch between multiple screens.

DevRocket is an iOS development panel plug-in that provides Adobe Photoshop with additional iOS specific tools and functionalities that are designed to assist key areas in iOS app design for both iPhone and iPad. A simplified solution to working between display resolutions, breaking down full ui designs into separate elements ready for Xcode and saving for the Retina display are just a few of the awesome features DevRocket brings to iOS designers currently using Photoshop.

You’ve probably seen Paper by http://www.fiftythree.com/, the app is pretty cool and the drawings look really nice and smooth. I’m working on my personal app that needs something similar, and after doing some research I’ve seen that there isn’t really anything like that available, some people try to use catmull roms etc. but that doesn’t look good enough. I will show you how you can achieve pretty cool drawing app.

WeViews is an Objective-C library for programmatically laying out UIViews.

Objective-C uses C’s math which you can find in math.h, however as we do program in different languages it is really annoying to remember by heart how the function names are abbreviated in each and every language. Thus comes here a short math overview of the math in Objective-C.

AirPlay mirror your iPhone 4S, iPad 2 or iPad 3 to any Mac running OS X 10.6+, wirelessly.

Two-file (.h / .m) useful components and utility classes that are dead-easy to drop into your iOS projects. ATPagingView, ATArrayView, ATByteImage

The zooming behavior of UIScrollView is counterintuitive and not terribly well documented – particularly when one is dealing with a tiled scroll view. Today I present a simple “infinite zoom” demo (over an admittedly pretty bland world) that I hope will helpfully illustrate a concise zoom implementation.

GestureML is the world’s first markup language for multitouch gesture-based interactions. It is flexible and extensible, giving you full control over gesture interaction in your apps during development and even after the app is published.

Introducing Clutch: an easy to integrate library for native iOS applications designed to help you develop faster and deploy instantly.

I’ve created an Xcode 4 project template to create universal (armv6, armv7 and simulator) static libraries for iOS

FMMoveTable is an UITableView subclass that provides moving rows by simply tap and hold an appropriate row without switching the table to it's edit mode.

SecureUDID is an open-source sandboxed UDID solution aimed at solving the main privacy issues that caused Apple to deprecate UDIDs.

Enter SMC - The State Machine Compiler. Now you put your state diagram in one file using an easy-to-understand language. SMC generates the state pattern classes for you. No more hand-maintained transition matrices. No more widely scattered switch statements. Instead, the state diagram is in one place, coded directly from the picture to the SMC language and is easily maintained.

OBStack is a very simple implementation of a stack data structure (last in, first out) in Cocoa.

It supports the following operations: * push: push a new object onto the stack. * pop: retrieve the topmost object and remove it from the stack. * top: retrieve the topmost object without removing it from the stack. * length/height/count: the number of items on the stack. * isEmpty: a boolean value if the stack is currently empty.

In OS X 10.7 and iOS 5.0, Apple added an inconspicuous new function named CGPathCreateCopyByStrokingPath() to the Core Graphics framework.

EMHint is an iOS class group that easily adds a spotlight-like effect to a view highlighting or hinting at something that may be important on the screen.The protocols of EMHintDelegate allow users to override many of the default actions and views. Tapping the black overlay fades it away. Great for quick "how to" or tutorials in your app.

PaintCode is a simple vector drawing app that instantly generates resolution-independent Objective-C drawing code for both Mac OS X and iOS.

Canalys today released the results of a recent App Interrogator survey of the top paid-for and free apps from the leading consumer app stores to clients of its App Store Analysis service. The survey reveals that the top paid-for Android apps are priced dramatically higher than those on iOS for the iPhone. In the US, to purchase the top 100 paid-for apps in the Android Market would cost $374.37 – an average of $3.74 per app – more than 2.5 times the cost of the top 100 paid-for iPhone apps. The top 100 iPhone apps would cost $147.00, or $1.47 on average per app.

prime31 Unity plugins provide the quickest, easiest way to incorporate iPhone and iPad native features into your application. Our plugin packages are designed to work synergistically with each other so you can use just 1 or all of them in any project.

Photo Picker+ a new free library for iOS that replaces the native photo chooser to let users select a photo from Facebook, Picasa, Flickr, or Instagram, in addition to the local Camera Roll or Photo Stream. It returns the photo in the exact same format as the native image picker on iOS and Android so it is very simple to integrate.

An iOS objective-c library template to recreate the gesture based interaction found from Clear for iPhone app.

CocoaPods manages library dependencies for your Xcode project.

You specify the dependencies for your project in one easy text file. CocoaPods resolves dependencies between libraries, fetches source code for the dependencies, and creates and maintains an Xcode workspace to build your project.

Ordinarily, you’d expect the UIColor to be in an autorelease pool, and so would survive until the end of the function. In this case, though, you can see ARC’s “avoid the autorelease pool” optimization is being used: if a method returns an autoreleased object, and the caller doesn’t otherwise need to hang on to it, ARC can avoid the trip to the autorelease pool. The method will return a retained object and objc_retainAutoreleasedReturnValue will dispose of it. That’s why the UIColor is not kept alive by the autorelease pool.

Pegasus is a lightweight open-source framework that allows you to build user interfaces for your Cocoa Touch projects in XML.

JBTabBarController aims to be a drop-in replacement of UITabBarController, but with the intention of letting developers easily customise its appearance. JBTabBar uses images for all UI elements except for the labels on TabBar items. This gives the Developer/Designer the freedom to customise the all aspects of the TabBar. In particular, the selected and unselected images for each TabBar item can be specified and are full colour images not clipping masks. The included example attempts to emulate the standard UITabBar design provided by Apple. The layer styles used to create the TabBar images in Photoshop are in the Extras folder. The project uses ARC and targets iOS 4.0+ devices.

EEToolbarCenterButton is a component to add a featured button to the center of UIToolbar. It handles button alignment, and helps you use buttom images whose height is larger than UIToolbar height.

GTM HTTP Fetcher makes it easy for Cocoa applications to perform http operations. The fetcher is implemented as a wrapper on NSURLConnection, so its behavior is asynchronous and uses operating-system settings on iOS and Mac OS X.

Articles about programming in Cocoa are many and in many places. The majority of them are of very high quality. To help out, I made this collected index, searchable by title or by article content. This page is very easy to maintain, so please email me any other articles out there that I've missed. Of course, make sure you also know about Apple's Cocoa docs! Also note that there are many Cocoa languages beyond Objective-C.

NRGridView is a grid-view UI component (built as a static library) which has been developed by Louka Desroziers, for Novedia Regions. How it works? Almost like UITableView works. You set a dataSource, and a delegate.. and you implement all @required methods. It also has a 'layoutStyle'. It means you can use it as a vertical gridView, or horizontal grid-view!

The GPUImage framework is a BSD-licensed iOS library that lets you apply GPU-accelerated filters and other effects to images, live camera video, and movies. In comparison to Core Image (part of iOS 5.0), GPUImage allows you to write your own custom filters, supports deployment to iOS 4.0, and has a simpler interface. However, it currently lacks some of the more advanced features of Core Image, such as facial detection.

Useful UIImage category for handling sprite sheets. This add-on smoothes the way of extracting images from a sprite sheet (texture atlas).

This can be useful in UIImageView animations where animationImages array has to be filled with a set of images representing frames.

Some interesting skeuomorphic UI design elements.

Tons of Cocos2D links

Beautifully done UIAlertView and UIActionSheet replacements inspired by TweetBot

One of the prettiest built-in views on the iPhone is the UIPickerView, which presents a slot-machine-like list of options. Unfortunately, this view isn’t particularly easy to use, as its default presentation takes up quite a bit of screen real-estate, and it’s not obvious how to resize it. Today, I’d like to talk about how to tame this view.

Add a Backend to Your Mobile App in Minutes

With our iOS and Android SDKs, you'll never worry about server-side development or deployment again.

A flexible, easy-to-use and complete iOS audio engine, built upon the efficient and low-latency Core Audio Remote IO API, written by one of the pioneers of iOS audio development, Michael Tyson.

SpriteHelper is a comprehensive and efficient Mac OS application which brings you a texture and a physics editor in one single package.

LevelHelper is a comprehensive and efficient 2d level editor created by Bogdan Vladu. It allows software programmers to build games for the iPhone, iPad and Android devices with very few programming  experience.

TouchDB is a lightweight CouchDB-compatible database engine suitable for embedding into mobile apps. Think of it this way: If CouchDB is MySQL, then TouchDB is SQLite.

Add a Backend to Your Mobile App in Minutes. With our iOS and Android SDKs, you'll never worry about server-side development or deployment again.

Anecdotally, developers consistently tell us that they make more money on iOS, about three to four times as much. To be sure, we pulled a sample of in-app purchase data from a set of top apps with versions on both iOS and Android, comprising of several million daily active users (DAUs). Running the numbers, we find that, on average, for every $1.00 generated on iOS, the same app will generate $0.24 on Android.

A category on UIView to easily apply a noise texture. Uses no external images or dependencies to make it very easy to drop into projects.

A fully customisable control to select telephone (but you can use it to select another data) as whatsapp application, it supports multiselection. Supports English and Spanish. Easy to use and customisable.

Mulberry helps web developers rapidly create content-rich native mobile applications. Powered by HTML5, CSS3, and JavaScript and built on top of PhoneGap, Mulberry transforms your content and data into a responsive, native, cross-platform mobile experience.

he Touch Gesture Reference Guide is a unique set of resources for software designers and developers working on touch-based user interfaces.

iSGL3D (iOS Scene Graph Library) is a 3D framework for the iPhone, iPad and iPod touch written in Objective-C, enabling the creativity of developers to flourish in a 3D world without the complexities of OpenGL.

In 2011, Smartphones are ubiquitous and everyone and his dog is writing mobile apps, but using apps when you're not in range of a fixed wifi hotspot or standing still in an urban area is often extremely frustrating. How often have you tried to refresh and found yourself staring at an interminable spinner that makes you want to throw your phone at the wall? Here's why (and a plea to app developers to do something about it!)

IOS UIImage processing functions using the vDSP/Accellerate framework for speed.

Objectify is a new Mac® application for Objective-C developers that dramatically speeds the everyday process of creating Cocoa class implementations based on JSON content.

Animatable is the easy way to create CSS3 animations and advertising for Webkit browsers on any platform or device — including Android, BlackBerry, iOS and WebOS.

I wrote a simple command-line utility, ShrinkPng, that takes a @2x.png file and halves its dimensions the way I just described. It scales with higher fidelity than Photoshop, so if you’ve been frustrated by the way Photoshop scales down your high-res images, give this tool a shot.

Generic popover implementation for iOS with same API as the UIPopoverController for the iPad, but configurable with custom background and available for iPhone/iPhone4

UILabel subclass which draws nicer shadows.

A little utility I just put together does that for you: Post Grabber detects POST data and generates an equivalent “curl” command that can be used in shell or Automator scripts.

Bare-metal webkit touch enabled scroll project. All JavaScript with no ext dependencies. It's called glovebox and it's open source, MIT You can check out a demo for ipad/safari/chrome here: http://bit.ly/GloveBoxDemo, it works on iPhone/android but in this demo I haven't laid things out very well for the smaller screens.

There are a number of reasons to use static libraries, but the main two are distribution to others without revealing source code, and code reuse across projects.

MWFeedParser is an Objective-C framework for downloading and parsing RSS (1. and 2.) and Atom web feeds. It is a very simple and clean implementation that reads the following information from a web feed:

This project aims to duplicate the methods present on Mac OSX which allow creation of NSAttributedString from HTML code on iOS.

This is useful for drawing simple rich text like any HTML document without having to use a UIWebView.

Simply put, appFigures is a reporting platform for iPhone developers that automatically downloads and visualizes iTunes Connect sales data with App Store reviews and ranks for all of their apps.

A random collection of useful bits of Cocoa, as found in Watson and in other sundry Karelia applications and testbeds. Feel free to adapt these for use in your Cocoa applications.

FTP/SFTP/WebDAV etc. for Cocoa.