The topic of this post is one that I’m sure many developers will know about especially since it is a footnote in several of the tutorials on the ARC tutorial and guide page on this site.

I’ve received so many inquiries about how to get open source libraries mentioned on this site and it’s surprising how many don’t know how to implement the -fno-objc-arc flag for using non-ARC enabled code within ARC enabled projects.

If you don’t know how to do this working with many of the open source projects on this site can be a living hell – so here’s the easy way to get nearly all of those Non-ARC enabled libraries working within your ARC enabled projects.

So here are two scenario’s you will likely run into when mixing ARC enabled and non ARC enabled code and how to solve them easily in Xcode 4.

Scenario 1 – You have non-ARC project that you want to refactor to enable ARC (using XCode’s refactoring feature), but there is existing code that you do not want to convert.

Here’s how to solve this, when you do the refactoring deselect the files that you don’t want to convert to arc, and Xcode will automatically add the -fno-objc-arc flag to those files.

1. Choose Edit->Refactor->Convert to Objective-C ARC in the Xcode menu.
2. On the Select Targets To Convert screen select your targets, then click the little arrow beside the target name to expand the list of files.
3. Highlight the files that you do not want to convert then right click (or ctrl-click) and select uncheck-all to deselect all the files you want to convert to ARC.  Then proceed as usual with the refactoring.

You can see this in the screenshot below where this has already been done with Cocos2D (btw, this is the easy way to get the Cocos2D template projects working with ARC):

Scenario 2 – You already have a project using ARC and want to add in some non-ARC enabled code, or you want to refactor the project yourself and don’t want to use ARC with some of the code.

I’ve seen this come up all over the internet in answers, and people asking where to add the -fno-objc-arc flag so here’s how it’s done.

1. Bring up the build phases tab for the appropriate target.arc1
2. Change the compiler flags for the specific code files that you do not want to enable ARC for to -fno-obj-arc (simply clicking on the compiler flags section beside the file, and enter -fno-objc-arc).

The flag will show up beside the file like in this screenshot if done correctly:

Continue as normal – the compiler now knows not to use ARC with the files that you flagged.

Conclusion

I can’t verify that it works in every case as there are some libraries with  things such as embedded projects that can mess things up, but in my opinion it’s good to try the easy way first – and I haven’t seen it not work with any of the newer open source libraries I’ve mentioned on this site in the last few months.

You might want to look at this template that allows you to create universal frameworks easily if you run into issues with the -fno-objc-arc flag and link to those projects as frameworks.

©2012 iPhone, iOS 5, iPad SDK Development Tutorial and Programming Tips. All Rights Reserved.

Objective-C blocks (closures) are something that I’ve mentioned in the past several times, most recently in this post about this massive open source collection of Objective-C blocks extensions, and another about a great guide on how to easily enable asynchronous UITableViewCell’s with blocks and Grand Central Dispatch.

It has been over a year since blocks were added to the iOS SDK, but still I see many searches on this site looking for beginner tutorials and guides on using blocks.  So if you’re still trying to understand blocks you’re not alone, and I’ve found a great reference resource for you.

The resource is a cheat sheet by Yannick Loriot describing how to create, declare, call, copy blocks, and more all on a single printable page with some nice examples.

You can find the cheat sheet along with a nice summary on using blocks on Yannick’s site here.

A very handy reference to have if you are still trying to understand the syntax of Objective-C blocks.

©2012 iPhone, iOS 5, iPad SDK Development Tutorial and Programming Tips. All Rights Reserved.

Several days ago I received some feedback from a user having issues creating a static framework using a tutorial that I mentioned over two years ago.

Since the tutorial is vastly outdated, I thought I would mention a much simpler way that I’ve since found for building frameworks.

You might be wondering why you would want to build a framework rather than simply building from source.  If you ever want to share some functionality with another developer without having to openly share all your resources then frameworks are the answer – specifically static frameworks – since you can’t include dynamical frameworks within your app store submissions.

The solution that I use now is a couple of templates rom Karl Stenerud:
https://github.com/kstenerud/iOS-Universal-Framework

With this script you can build universal (arm6, arm7, and simulator) frameworks and – as Karl refers to them – build both Real and Fake frameworks.  Templates for both types are included on the Git repository – the real framework template builds the typical static framework you’d expect while the fake framework has the advantage of not requiring you to edit your Xcode project files, but there are some complications.

Full details about the different frameworks you can create with the templates and instructions included on the Github page.

If you’d like to figure out how to do all this yourself, Diney Bomfim has written an excellent tutorial on his site:
Universal Framework On iPhone OS .

As you can see the template makes things a lot easier.

©2012 iPhone, iOS 5, iPad SDK Development Tutorial and Programming Tips. All Rights Reserved.

If you’ve been working with UITableView’s then you’ve likely run into a situation where you had multiple groups of cells that the user has to scroll an excessively long way down the screen to use.

I came across a library today that is very handy for this situation, it allows you to make each section of the tableview collapsible with ease, and each segments collapses and expands with a very smooth and natural animation.  The library is very easy to use, and comes with a detailed step by step tutorial so that you can implement it quickly.

You can find the library along with the tutorial on Codeproject here:
Reusable collapsable table view for iOS

Very handy if you have a grouped table view that has gotten too long.

©2012 iPhone, iOS 5, iPad SDK Development Tutorial and Programming Tips. All Rights Reserved.

The Evernote app is an excellent note taking app for iOS devices (and the Mac platform).  It is also very easy to use and well designed.  One of the features within the Evernote app is a keyboard button which allows you to hide and show the keyboard when pressed.

I’ve found a tutorial demonstrating how to duplicate the Evernote style keyboard.  What I find interesting about this tutorial is that not only does it show how to create the sliding door image stretch effect, and perform button animations, but that it mentions a Ruby script that allows you to easily grab images from an app.

Of course you not want to do this within an app you are submitting to the app store, but if you want to learn how to implement some cool feature not having to create your own placeholder images is a big time saver.

You can find the tutorial here:
Creating a Keyboard Show Hide Button

The script mentioned in the article can be found on Github in this nice collection of open source goodie sfrom iDevrecipes.com in the utilities folder:
https://github.com/boctor/idev-recipes 

A pretty nice effect, and a very handy script.

©2012 iPhone, iOS 5, iPad SDK Development Tutorial and Programming Tips. All Rights Reserved.

There are so many useful open source libraries available for iOS devices.   I haven’t seen one with such a wide variety of uses as this toolkit.

With this toolkit there are over 40 useful open source (Apache licensed) libraries that you can use in your iOS apps.  All are useful, and the library is designed so that you won’t need to clutter your app by including a massive number of files – in most cases you only need to add a single class to your app in order to add the functionality.   You just need to add what you want to use within your app.

The open source project is known as the Cooliris-Toolkit from Cooliris, and has already been used in several apps by Cooliris including their fantastic Discover Wikipedia In Magazine app.

Here’s a listing of the classes within the toolkit taken from the project homepage:

• ApplicationDelegate: This classes offers numerous built-in functionalities for a UIApplication delegate in cooperation with the Logging and Task classes. Your application delegate class should subclass this class instead of NSObject to benefit automatically from all these features.
• AutoresizingView: UIView subclass that automatically resizes a content subview using a “center”, “resize”, “aspect-fit” or “aspect-fill” method.
• BasicAnimation: Simple CABasicAnimation subclass that allows to specify per-instance delegate and callbacks on animation completion.
• CameraViewController: UIViewController subclass to replace UIImagePickerController to take photos with customizable user interface, image scaling and EXIF metadata (including GPS location) inclusion.
• Crypto: Provides C function wrappers for MD5 and SHA2-256 hash computations.
• Database: Implements a powerful SQLite Objectice-C wrapper with automatic schema creation from class properties.
• DataWrapper: Simple NSData subclass that allows to wrap a block of memory and provide a custom C callback for release.
• DiskCache: Manages a cache on disk of NSCoding compatible objects or raw data files which can be purged to a maximum size.
• DocumentView: Displays and manages layout and user interaction of a set of “page-type” subviews arranged horizontally.
• ExtendedPageControl: Implements a page control like the one on the home screen of iOS.
• Extensions_AmazonS3: Category on NSMutableURLRequest to sign HTTP requests for Amazon S3.
• Extensions_CoreAnimation: Categories on Core Animation classes to implement various convenience features.
• Extensions_Foundation: Categories on Foundation classes to implement various convenience features.
• Extensions_UIKit: Categories on UIKit classes to implement various convenience features.
• FileSystemView: Subclass of GridView that displays the contents of a directory.
• FormTableController: UITableView subclass that implements a form with text, password or checkbox fields.
• GridView: Displays and manages layout and user interaction with a grid of subviews.
• HTTPURLConnection: Subclass of NSURLConnection that implements synchronous HTTP operations and offers features like downloading to disk or resuming downloads.
• ImageCell: UITableViewCell subclass to display images.
• ImageUtilities: Low-level C functions to perform graphic operations on CGImages.
• InfiniteView: Displays and manages layout and user interaction of a set of “page-type” subviews arranged both horizontally and vertically in an infinite presentation.
• Keychain: Objective-C wrapper to store and retrieve passwords from the Keychain.
• LibXMLParser: Objective-C wrapper for LibXML.
• Logging: Powerful logging facility with history recording and playback, and well as remote logging over Telnet.
• MapAnnotation: Basic MKAnnotation conforming class to use with MapKit.
• MovieView: Loads and displays a movie from a URL.
• NavigationControl: Implements a navigation control with customizable markers and thumb.
• NetReachability: Objective-C wrapper for the System Configuration reachability APIs.
• OverlayView: Displays a simple pop-over view with an arrow at a given location.
• PubNub: Clean and simple Objective-C interface for http://www.pubnub.com/.
• RemoteUpdater: Allows one-way synchronization of “extra content”, typically Zip archives which get decompressed on arrival, from a remote server to the application.
• RichString: Basic replacement for NSAttributedString that allows archiving of itself and its attachments.
• ServerConnection: Provides an abstract state-machine for applications that needs to be continuously connected to a server and automatically reconnect / disconnect depending on network conditions.
• ShakeMotion: Wrapper around UIAccelerometer to detect shake motions.
• SliderControl: Implements a slider control with customizable graphic assets.
• SmartDescription: Replacement for NSObject’s -description that automatically prints the values of the object’s properties.
• SwitchCell: UITableViewCell subclass to display switches.
• Task: Implements a powerful background tasks management system for your application: task dependencies, task groups, independent completion delegates… Works on iOS 3.2 using threads and GCD on iOS 4.0 and later.
• TextFieldCell: UITableViewCell subclass to display text fields.
• TextIndex: Offers a simple text indexer for Western languages.
• UnitTest: Base class to implement unit tests.
• WebViewController: UIViewController subclass that displays a UIWebView along with back and forward buttons.
• WorkerThread: Allows to start and wait for completion of background threads in an atomic way.
• ZoomView: Displays a content subview (typically a UIImageView) with automatic pan and zoom behavior.

You can find the checkout page here:
http://code.google.com/p/cooliris-toolkit/source/checkout

This is definitely a toolkit that I will be using again and again.

©2012 iPhone, iOS 5, iPad SDK Development Tutorial and Programming Tips. All Rights Reserved.

Not too long after support for blocks (or closures as they were originally named) was added into the iOS SDK I posted about a tutorial and set of examples on blocks.  If you were familiar with blocks from using them in another language such as Python or Ruby then you probably understood things pretty quickly with those examples.  If you are unfamiliar with blocks those examples should give you a good grasp of the basics.

I’ve found another tutorial that gives a good overview of blocks, and tips for beginners, but also gets into other topics not included in the previous tutorial such as how blocks are used in concurrency programming.

The tutorial is from Jim Dovey and can be found here:
Programming With Blocks An Overview

If you’ve been having trouble understanding blocks – and why and when to use them this tutorial is great.

©2012 iPhone, iOS 5, iPad SDK Development Tutorial and Programming Tips. All Rights Reserved.

Not too long ago I mentioned a  great open source projects utilizing Core Text and NSAttributedString to replace the UITextView component for easily formatted editable text.

I’ve found a component that was designed to be a drop-in component for UILabel replacement that is very easy to use, and includes an excellent example basically showing everything you need to know.  No need to fiddle around with things,  if you just want to add some formatted text quickly this is a great solution.

Here’s a screenshot from the demo project:

The project is TTTAttributedLabel From Mattt Thompson and can be found on Github here:
https://github.com/mattt/TTTAttributedLabel

I’ve also seen OHAttributedLabel which looks great too:
https://github.com/AliSoftware/OHAttributedLabel

That one is not a drop-in replacement, but rather a set of helper libraries for applying formatting to your UILabel’s which is great for making existing UILabel’s look good.

©2012 iPhone, iOS 5, iPad SDK Development Tutorial and Programming Tips. All Rights Reserved.

If you’ve ever wondered how to code gesture recognition for complex shapes I’ve come across a couple of open source libraries that should be a great deal of help.  This goes well beyond finger swiping.

This library is based on the $1 gesture recognizer which I remember being discussed quite a bit a few years back because not only did it run efficiently,  but allowed you define the templates to recognize complex shapes very easily.   The $1 gesture recognizer only recognizes 1 single stroke from the user.  The $1 gesture recognizer was later expanded on to become the $N multistroke gesture recognizer.

Brit Gardner has taken the $N gesture recognizer and created an Objective-C implementation of the code.

You can read about complex gesture recognition, and why Brit decided to use the $N gesture recognizer on his site in these posts:

Complex Gesture Recognition in iOS – Part 1: The Research
Complex Gesture Recognition in iOS – Part 2: The Implementation

You can find Brit’s Github for the Objective-C $N gesture recognizer here:

https://github.com/britg/MultistrokeGestureRecognizer-iOS

Adam Preble has created an implementation of the $1 gesture recognizer which can be found here:

https://github.com/preble/GLGestureRecognizer

You can try out the javascript versions, check out the full pseudocode, or download other versions of the gesture recognizers from the University of Washington here:

The $1 Gesture Recognizer
The $N Multistroke Gesture Recognizer

I’ve received e-mails a couple of times over the years asking about how some drawing games were created on the iPhone.  If you are looking to make that kind of game this should help give you a head start.

©2012 iPhone, iOS 5, iPad SDK Development Tutorial and Programming Tips. All Rights Reserved.

In the past I’ve posted about creating iOS style buttons mentioning this tool, and this library which allow you to draw glossy buttons similar to those found in most iOS apps.

The basic calculator app however has different buttons.  They have a rounded gloss at the top, and a steady gradient all the way down the button.  You may have noticed when using the app that when you press the buttons there is a much more noticeable effect as the button look seems to reverse giving the impression that the finger has caused the button to reverse.

A developer named the Code Padawan has written up a quick tutorial, and provided sample code demonstrating how to duplicate this effect.

You can find their tutorial here:
iPhone Glossy Buttons

The effect is done entirely using core graphics so no need to break out Photoshop or any other tool.

[via Ole Begemann]

©2012 iPhone, iOS 5, iPad SDK Development Tutorial and Programming Tips. All Rights Reserved.