As developers we spend most of our lives dealing with broken and barely-functional software: our own software. We do our best to make the applications we develop somewhat less broken and try to add features to make it functional. And once we finally get our software working bug-free and functioning stably, what do we do? Do we bask in the joy of a stable app and spend countless hours enjoying that moment? No, we move on to v1.1 or v2.0, adding more features and consequently more bugs. It’s kind of sad if you think about it.
Since much of our lives are spent with applications in various states of brokenness, understanding how to debug our software and catch those exceptions that arise is vital to getting our applications to a stable state so we can release, consequently moving on to create a whole new set of bugs that need to be fixed.
Here are some basic tips and tricks to make your life easier dealing with Xcode 4, and tracking down those places where your code runs off into the bushes.
Continue reading “Back To Basics: Simple debugging tips in Xcode”
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. Continue reading “Building a static library with Jenkins”
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.
Continue reading “Using GCD and Blocks Effectively”
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.
Continue reading “Back to Basics: Using KVO”
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.
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.
Like most developers, I look to Apple’s default application templates to get up-to-speed on what would appear as being the Right Way™ of developing apps on iOS. In practice however what you need to realize is Apple’s templates are meant to be the easiest introduction to a set of tools that can be fairly complicated for beginners to understand. Core Data is one of those areas. The problem is when you try to grow your application you’ve built on top of Apple’s sample template. You’ll experience some annoying growing pains, and will need to give your code a thorough washing and a fresh coat of wax to be able to mature your application.
In my code I’ve learned to share and reuse my classes with other applications I’m writing by encapsulating a lot of the boilerplate into reusable classes, as well as wrapping my whole Core Data model in a reusable static library. This wasn’t the most intuitive thing to get right, but now that it’s done it was really worth the effort. Let me show you how it’s done.
I’ve written about building iOS applications with
Hudson Jenkins, but until recently there hasn’t been a convenient way of getting those applications to your testers. Of course the most important part of your build output will be the app bundle you send to Apple’s iTunes Connect web interface, but throughout your development cycle you’ll want to test your app. Sure you could build and deploy a debug build straight to your own personal device, but you get the most benefit from having other people beta test your app.
With recent releases of Xcode and the iOS SDK, Apple improved their AdHoc distribution support with two main enhancements:
- Mobile provisioning files can now be embedded in the App’s IPA itself, meaning you don’t have to maintain and update separate .mobileprovision files separately;
- A specially-formated manifest Plist file can be created that, when linked to properly, allows test devices to install new versions of your AdHoc app without needing to plug into a computer to sync the app using iTunes.
These improvements are huge, but require some changes to your build scripts and your Continuous Integration environment. I’d like to show you how to do this in your own installations, and show you some options for how to distribute your apps to your testers.
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
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