One of my pet peeves is Open Source iOS libraries distributed as just a collection of Objective-C classes, rather than being bundled as a static library. I know a lot of people prefer it that way, but from a maintainability standpoint it really doesn’t make much sense to me. So when I’m faced with another library I want to use that doesn’t have a static library readily available for it, I typically wrap it up in my own Xcode project, check it in to Github, and configure my Jenkins continuous integration build server to compile it for me.

I thought I’d walk you through the steps I go through to make this happen, so you can use this technique too. (more…)

With iOS 4.0 Apple introduced two new technologies to the iOS platform: Grand Central Dispatch, and blocks.  Simply put, it is to multi-threaded programming what fire is to a barbecue.  Sure you can do without it, but the end result is much better.

Despite all this, developers still seem to avoid using it. Some of the reasons for this, off the top of my head, could be backwards-compatibility for older versions of iOS, unfamiliarity with the funky syntax it uses, or simply a lack of practice.  The biggest thing I find however is a general misunderstanding about the importance of multi-threading among new developers, which was made worse by the difficulty of dealing with threads before blocks and GCD was released.

Fortunately there’s no reason to avoid multi-threaded programming in iOS, but before I dive into the specifics I’d like to point out just how important it is to use an asynchronous approach to development on iOS, or any mobile platform in general.
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One of the things I like most about Apple’s iOS SDK is the consistent and easy-to-use API they provide.  Across all their different frameworks there’s a pattern at work that makes using their classes easy to understand.  This is due in part to the simplicity for configuring those objects.  In most cases you don’t need to call cryptic methods to setup or teardown classes.  If you want to change a label’s font, you just set a property.  If you want to add a new set of tabs to a UITabBarController, you simply have to assign an array of view controllers to the “viewControllers” property and away you go.
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Following up on my previous post in this series, I’m going to continue talking about beginner topics that I and many other developers take for granted. So for this entry in my “Back To Basics” series I’d like to talk about UITableViews, and how to simply and easily construct one without convoluted or confusing code.

This topic in particular is something I’ve struggled over in the past and never managed to find a clear example for how to get started. Certainly there’s a lot of examples to show how to construct a table view, how to create a datasource for it, and the basics for how to construct cells. But hardly anyone tells you how to easily and conveniently construct a menu of options without going down a maze of twisty passages.

So today I’ll show you how you can use simple “typedef” structures to describe and control a simple menu of options.

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These days I’ve been working on some fairly advanced iOS development techniques on my various projects: I’ve taught myself (badly) about Core Audio, I’m learning OpenGL, I’m developing a series of applications using Core Data, asynchronous parsing of JSON from a streaming HTTP connection, etc. It’s extremely fun and easy once you understand the basics.

What I tend to forget however is that you have to crawl before you can walk, and many people still struggle with some of the simpler techniques that I’ve learned that may not be so obvious, even when reading books or tutorials on Objective-C programming.

Since my previous series of articles on Core Animation (Part 1, Part 2, Part 3, Part 4) were so well received, I thought I’d do another series of articles titled “Back To Basics”.

So without further ado, I give you the first part in my series: Positioning UIViews.

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This is the fourth in a series of posts I’m writing on animating iOS interfaces using Core Animation. In the first post I created a planetary orbit demo using nested CALayer objects. The second post showed how to dress up a UI by animating an image. The third post shows how you can trigger animations in response to button actions.

This post will show how you can create the beginnings of a full game using Core Animation combined with CAShapeLayer and UIBezierPath objects.

Read on to see more

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This is the third in a series of posts I’m writing on animating iOS interfaces using Core Animation. In the first post I created a planetary orbit demo using nested CALayer objects. The second post showed how to dress up a UI by animating an image.

This time I’ll show how you can trigger animations in response to button actions to illustrate to the user that an action is taking place.

Read on to see more

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This is the second in a series of posts I’m writing on animating iOS interfaces using Core Animation. In the previous post I created a planetary orbit demo using nested CALayer objects.

This time I’m going to show how you can dress up a UI by creating a simple effect using an image and Core Animation.

Read on to see more

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One of the greatest things about the iOS platform and applications people see on it is its beauty. Smooth gradients, consistent transitions, and animations that illustrate the transition of UI elements from one state to another. Animations are more than flashy eye-candy; they tell the user what’s happening. If an element is being deleted, instead of it simply disappearing it fades or slides out of view. Unlike traditional desktop or web applications where a “2 items deleted” statusbar message is necessary, these animations are in many cases enough.

Knowing where to start with animations can be a problem for developers though, because there’s many different steps involved. Instead of walking you through it fully here in the blog, I highly recommend you watch the WWDC 2010 videos on the topic. I truly mean it; anything I do here will simply be a rehash of that material, and I don’t see the point in reproducing perfectly good documentation unnecessarily.

• WWDC 2010 Session 123 – Building Animation Driven Interfaces
• WWDC 2010 Session 424 – Core Animation in Practice, Part 1
• WWDC 2010 Session 425 – Core Animation in Practice, Part 2

Read on to see more

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Plenty of times in applications, especially on mobile devices, you just need to tell your users to hold their horses and wait while your application processes something in the background.  Maybe you need to query some data from a remote server, save a file to disk, or maybe you just need to do some number crunching.  Whatever the reason, you don’t want your user to think the program has crashed if you don’t give them some sort of visual feedback that you’re busy and they just have to wait a few seconds.

PhoneGap provides a few methods to handle just this task. There’s four methods within the Notification class that are of interest.

1. navigator.notification.loadingStart()
2. navigator.notification.loadingStop()
3. navigator.notification.activityStart()
4. navigator.notification.activityStop()

Modal loading messages

Modal loading indicator

The easiest approach to take when making your users wait is to show a modal loading dialog, one that doesn’t let the user interact with the application until you’re done.  There’s a lot less for you, as a developer, to manage when the user isn’t allowed to poke around on buttons when you’re updating the display.  Asynchronous operations are a lot simpler when you’re in control.

The loadingStart() and loadingStop() methods do just this.  They put up a modal semi-transparent layer over top of your application, with a “Loading..” spinner message. You simply call the first method when your application is about to do something, and when it finishes you call the second.

Here’s an example of how to use it.  This will load a remote HTML document and place its contents into a node in your PhoneGap application.

Not only does this make it easier to integrate external content into your PhoneGap application, but it guarantees your user is informed that it’s actively working. As a final bonus, if your external web site doesn’t respond, or if the user doesn’t have an Internet connection, the modal loading screen will close after a timeout.

Asynchronous loading messages

Asyncronous activity loading indicator

Sometimes you want to tell your user that the application is busy, but you still want to continue using the app anyway.  If your app doesn’t turn off the top statusbar (where the time, reception, and battery status is displayed), you can control the busy indicator from within PhoneGap.  Just like the above example, you just have to call the appropriate PhoneGap JavaScript methods.  In this case, just update the above example with these messages:

navigator.notification.activityStart();
// Do something that might take a while...
navigator.notification.activityStop();