Tag Archives: Objective-C

The Dirty Little Secret of iPhone Development

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This is happening right now, at a web agency near you.

The dot-com boom of the 90′s spawned a brand new generation of coders and software developers, including me, by the way. While before that time the term of “software developer” might have been reserved to system programmers fluent in C, COBOL, C++ or other languages, right now the vast majority of developers I know spend their time writing web applications, either public or in a private intranet, in J2EE, ASP.NET, Rails, PHP, you name it.

I have said before that writing web applications should be taken as seriously as writing desktop systems. Call me names if you want, but I’m a big fan of Joel’s Test.

However, after all this years, after the Chaos reports, after Peopleware, after the Mythical Man Month, people still treat quality as an afterthought. And also complain about how much software sucks, how expensive it is, and how late it arrives, by the way. Now that the iPhone SDK is widely available, that the App Store is selling more apps that we could have had imagined 6 months ago, many web agencies want to jump to native iPhone development contracts, which are hype and nice and pricey and whatnot. Which is only going to make things worse.

The dirty little secret in this story is this: iPhone development looks more like developing applications for a desktop operating system, and less, much less than web development. And I’m frightened to see some small shops (and even bigger ones), who never attained a real level of professionalism or quality in their software tasks, starting projects and realizing, later, when they are over budget and behind schedule, that this kind of applications requires a different mindset.

Continue reading →

REST and Objective-C, again

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I’ve just uploaded some code derived from the Objective-C wrapper I’ve shown in this post. You can find it in the “Projects” section, as usual and it’s simply a wrapper around the URL loading system of Cocoa, both for Macs and iPhones, providing a custom delegate protocol, so that you can handle the events raised by the wrapper:

[source:C::firstline(13)] @protocol WrapperDelegate

@required - (void)wrapper:(Wrapper *)wrapper didRetrieveData:(NSData *)data;

@optional - (void)wrapperHasBadCredentials:(Wrapper *)wrapper; - (void)wrapper:(Wrapper *)wrapper didCreateResourceAtURL:(NSString *)url; - (void)wrapper:(Wrapper *)wrapper didFailWithError:(NSError *)error; - (void)wrapper:(Wrapper *)wrapper didReceiveStatusCode:(int)statusCode;

@end [/source]

The sample project, available in the zip file, shows how a simple Cocoa controller can interact with the Wrapper class as required. Enjoy!

Update, 2008-10-26: After a bug report from StuFF mc I’ve updated the code for a better support of POST and PUT requests, and also added a sample PHP file for a quick test of the functionalities.

Playing with HTTP libraries

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It’s fun to find out how to tackle the same task in different programming languages; in this case, it’s all about doing HTTP requests over a network: fortunately, there are networking libraries in virtually all major programming languages. In my current project, I’m generating wrappers easing the access to the core of the project itself, a RESTful API. This way, developers interested in using the API can just take a wrapper, include it in their projects, and start coding right away. No need to know this (relatively low-level) stuff; just use the API. The wrappers themselves are auto-generated from the API definition itself, but that’s another story ;)

Below there is a sample of the different ways I’ve found to do a network access to a remote server, using HTTP Basic Authentication and a couple of headers, in PHP, Ruby, Python, JavaScript, and even Objective-C! I’m even generating ActionScript 3.0 code, but I’m not a Flash coder :) So I’ll post the wrappers that work best at the moment, and in the future I’ll include other examples, particularly for .NET, C++ and Java.

In all the cases below, there is a “request” function or method that takes an HTTP verb (GET, POST, PUT, DELETE, etc), a URL (without the slash “/” at the beginning) and some parameter data, in the form of a dictionary. The function wraps the underlying libraries of each programming language, offering a simpler interface, and allowing for HTTP Basic Authentication (for HTTP Digest Authentication it would be much, much more complex!). There are synchronous (useful for server or command-line applications) and asynchronous versions (for GUI systems). Off to the code! Continue reading →

Null References

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There’s an interesting discussion going on these days on Ruby blogs about, basically, how to avoid one of the most common, annoying, easy-to-create bugs in any programming language: calling a method on a null reference (or pointer, depending on your language).

This single issue happens all the time, in garbage-collected and non-managed languages, static and dynamic, weakly and strongly typed; you have a handler variable “pointing” to an object, and before calling any methods on it, you’d better be sure that the object is there; you end up using assertions, “if” statements (and all of its variants), boilerplate code all over the place, when everything you want to do is to call that damn method. It’s frustrating, time-consuming and oh so common that we just try to not to think about it anymore. Continue reading →

How to Grab (or Capture) your Screen with Cocoa?

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Lately I got curious to know how could I grab the entire desktop of my computer, and save it into a file, or display it into an NSImageView component. I started to look around on the web and discovered that:

  • There’s no direct support for that in Cocoa
  • There’s a lot of different ways to do it, both supported and unsupported, cross-processor and not, easy and complicated

I have found several useful resources in my quest, like this one, this other one, and finally this one. But what I wanted most was a complete application to play with, so what I did is to put all the different implementations I’ve found in one single application, called “ScreenshotDemo”:

Amazingly, the approach that seems the ugliest turned to be the most appropriate, that is, using an NSTask instance wrapping the /usr/sbin/screencapture utility. With it, the application feels lighter, easier to maintain, in the true, purest Unix style: using a collection of small utilities, all chained one to the other, is better than having an overbloated tool that does everything, but just bad.

You can just download the (universal) binaries and the source code from the ScreenshotDemo Project page.

By the way, for those that would like to do the same in C#, like me :) just check out this code. It isn’t much easier in .NET, as you can see ;)

And last but not least, here’s how to do it in wxWidgets, explained by Julian Smart, the creator of this incredible library.