Cocoa

 
13
Nov
2008
 

Landscape Tab Bar Application for the iPhone

by Matt Long

As you develop applications for the iPhone, you will likely use the project templates provided in Xcode. One such template, called “Tab Bar Application” helps you get a tab bar application set up quickly, but by default the application it generates only supports portrait mode for display. So how can you make the application also support landscape or even only support landscape? In this post we will address that question.
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5
Nov
2008
 

Core Animation Tutorial: Interrupting Animation Progress

by Matt Long

Starting and stopping animations in Core Animation is as simple as adding and removing your animation from the layer upon which is being run. In this post I am going to talk about how to interrupt animation progress and how to determine whether an animation completed its full run or was interrupted. This is accomplished with the animation delegate -animationDidStop:finished.
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27
Oct
2008
 

Announcement: Marcus’ Core Data Book Just Went Beta!

by Matt Long

Core Data BookA lot of hard work has gone into this book already and I see it becoming the definitive text on the subject of Core Data. The release date is slated for March 30, 2009, but it’s great to see it in beta. If you want to pick up the beta in PDF, it is available now from Pragmatic here: Core Data: Apple’s API for Persisting Data under Mac OS X.

While new Cocoa programmers will find it a great help to getting started quickly with Core Data, the book also covers some really interesting and advanced topics such as data versioning and migration, Spotlight/Quick Look integration, Sync Services, and multi-threading. You can really see Marcus’ command of the subject shine in these chapters which are already available in the beta.

Give Marcus some feedback on the book as it progresses. It’s going to be a great reference for any Cocoa Developer looking to harness the power of Core Data.

$21.00 for the beta PDF
$41.35 for the beta PDF plus hard copy when it’s released in March.

Mad props to Marcus. Congratulations!

 
25
Oct
2008
 

Core Animation Tutorial: Slider Based Layer Rotation

by Matt Long

It is often helpful to create a custom control for you application that will display a value as a level like a gas gauge shows how full your tank is. In this post I will demonstrate how to create a three layer tree that will show the current rotation of a circular layer as the value from a slider (NSSlider) is updated in real time. The layers include the root layer, the rotation layer, and a text layer that will display the current rotation in degrees.
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24
Sep
2008
 

Core Animation Tutorial: Core Animation And Quartz Composer (QCCompositionLayer)

by Matt Long

Last night at NSCoder night, Fraser Hess was asking question about being able to draw in a Quartz Composer View (QCView) about which none of the rest of us had any knowledge or experience. As I’ve been doing a lot with Core Animation lately, I asked him if it was possible to just make the view layer backed and start adding layers to it. Fraser hasn’t worked with Core Animation much yet, so he was unsure. The other three of us set to looking at docs and making demo apps. The race was on… Oh. It’s not a race? Sorry about that. I thought we were practicing for Iron Coder…
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10
Sep
2008
 

Core Animation Tutorial: Rendering QuickTime Movies In A CAOpenGLLayer

by Matt Long

I’ve been experimenting a great deal lately with OpenGL and QuickTime trying to see how the two technologies work together. It’s been a bit challenging, but fortunately Apple provides two really great resources–number one, sample code. I’ve been able to learn a lot just from the samples they provide in the development tools examples as well as online. And second, the cocoa-dev and quicktime-api lists are great. Lot’s of brilliant people there who are willing to share their knowledge. It’s very helpful, prohibition to discuss the iPhone SDK notwithstanding.

Getting two technologies to work together can be a challenge especially when the bridges between the two are not necessarily clearly laid out in documentation. As I pointed out Apple provides some excellent sample code to help you along, but there is no hand-holding approach to any of it. I actually appreciate that having come from the Windows world as it seems that there all you get sometimes is hand-holding where Microsoft doesn’t trust you, the developer to figure things out and really own what you’re doing. But I digress (wouldn’t be a CIMGF post if I didn’t dig on MS a bit).
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4
Sep
2008
 

Cocoa Tutorial: Creating your very own framework

by Marcus Zarra

There are numerous situations where creating your own framework is advantageous. Perhaps you have a block of code that you use repeatedly in many different projects. Perhaps you are building a plug-in system for your application and want the infrastructure to be available both to the application and to any plugins that are coded.

A Cocoa framework is another project type in Xcode. The end result is a bundle, similar to an application bundle. Inside of this bundle is the compiled code you wrote and any headers that you want exposed. The headers are important. Without them, just like any other piece of Objective-C code, it is very hard to code against.

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27
Aug
2008
 

Cocoa Tutorial: Sync Services without Core Data

by Marcus Zarra

Sync Services have come a long way in Leopard. Before Leopard it was an extremely complex operation that was almost completely manual. Needless to say, this sucked and it was probably one of the reasons it was shunned by most developers.

If you are using Core Data in a Leopard application then Sync Services is so trivial that you should be syncing if it makes sense. In this article we are going to cover syncing in a non-Core Data situation as that is quite a bit more complex.

If you have read the Sync Services documentation then you know it is complex. Let me dispel an illusion right away. It is hard. It is not poor documentation, syncing is very hard and very few people get it right. Take a look at Omnifocus to see an example of a company thinking it is easy and losing data. Therefore if you are expecting this subject to be trivial you will be disappointed.

In this example we will be syncing with the bookmarks schema and displaying them in a simple outline view. The outline view itself will be editable and those edits can be synced back. Not terribly useful but provides a very simple example.
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24
Aug
2008
 

Cocoa Tutorial: C# LINQ Or Cocoa Key Paths And NSPredicate

by Matt Long

I think it may be helpful to demonstrate how to perform certain tasks in Cocoa from the perspective of a Windows programmer. And considering that I was one, it seems that I may be able to help shine some light on some of the issues that programmers face when coming over to the Mac platform. In this post I want to highlight one of Objective-C’s coolest features, key-value coding, in light of a Microsoft technology that was introduced in the most recent edition of the .NET framework (v3.5).

Microsoft’s new technology called LINQ, which stands for Language Integrated Query provides a way for developers to massage data collections using a SQL-like syntax that is built right into the language. You can perform simple data queries like this.

Notice how it has a very SQL like syntax. It’s actually very powerful and robust. There are a lot of capabilities. Take a look at the 101 LINQ Samples page if you would like to see more examples. What’s most interesting to me though is that the ideas behind this technology are not new.

If you’re new to Cocoa, you’ve probably heard of key-value coding and have probably even worked through some examples of its use without really understanding it. While the usage is different between the two, these technologies provide similar capabilities. Objective-C just had them first.
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18
Aug
2008
 

Cocoa Tutorial: libxml and xmlreader

by Marcus Zarra

Let us pretend for a moment that NSXMLDocument was not available to your Cocoa application for some reason. Perhaps you have low memory requirements, perhaps you are running on a slimmed down version of OS X. Whatever the reason, for the purposes of this exercise, NSXMLDocument does not exist.

Let us now assume that we have a requirement to parse an xml document quickly and without loading the entire tree into memory in a object structure. In a situation like this libxml comes in handy. Unfortunately it is quite a bit more complicated than calling alloc init on NSXMLDocument.

libxml is a C library that is included with all current releases of OS X. With this library we can quickly read in a document, scrape the information we need out of that document and avoid loading the entire tree into memory at once. In addition, libxml (and more specifically xmlReader) does this very quickly, far faster than NSXMLDocument which is very useful when you have a lower end CPU. In this project we are going to create a simple application that reads in an xml file containing a list of people, their names and their ages. For the purposes of demonstration we are going to load that data into an array of NSDictionary objects and display it in a standard Cocoa window.

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29
Jul
2008
 

Cocoa Tutorial: Windows OOP vs Cocoa MVC

by Matt Long

Encapsulate everything! Right? Or not. I was watching the Cocoa developers email list today and saw a post asking for help getting two views to communicate between one another. Having been a Windows programmer for longer than I’m willing to admit, I recognized the question as it was one that I also had when I moved to Objective-C on the Mac. I think I can ask the question more succinctly now than I could then. Better phrased it would be “I have a dialog object that I instantiated and obtained some data from the user with it. I now need to get that data out of my dialog object back into my main window object where I can do something with it. How can I get the information back into my main window from the dialog?”

In Windows, more specifically C# .NET, you would create a new window by adding a Windows Form object that you could then edit with the designer adding various controls pretty easily. But once that window was created, you now need to create an instance of it in your main window code and then provide public accessors to assign or obtain data between the two windows. The window class generated by the Windows Form template encapsulates everything for you. It certainly makes the code look clean, but it really breaks the Model View Controller paradigm so it’s no wonder Windows programmers (myself included) have a hard time shifting their way of thinking.
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16
Jun
2008
 

Cocoa Tutorial: Custom Folder Icons

by Matt Long

This is just another one of those things that seems like it ought to be a simple little code snippet and you’re there, but in actuality it’s just not the case. I am building an exporter for my application that will export a movie project in iMovie HD format. I want to mimic the file format exactly and one of the things I noticed about the directories that are stored inside iMovie HD‘s custom format (select ‘Show Package Contents’ from the context menu in the Finder) is that they have custom icons assigned to them. So the problem to solve was how to do that programatically. Here is what I’ve found.
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29
May
2008
 

Coding Practice: Cleaning up the default Core Data project

by Marcus Zarra

In this entry I am going to do something a little different. Instead of showing some wicked code, I am going to reformat one of Apple’s default templates.

Apple writes some amazing code. Unfortunately a lot of their templates demonstrate simply terrible coding practices. What is worse, people take these templates and assume that they are the proper practice for coding in Objective-C and propagate that poor code into their own projects.

The first example I am going to tackle is the AppDelegate class that is auto generated in the Core Data template. This is not the Core Data Document template but the standard application template.

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24
May
2008
 

Cocoa Tutorial: Working With Application Resources

by Matt Long

For most simple applications using and managing resources is handled seamlessly and you don’t ever have to intervene programatically. There are times, however, as your applications begin to mature that you need to access resources directly. Doing so is pretty straightforward, but I thought I would document it here–if for no other reason than to have it written down somewhere for the next time I need it. I hope it might be helpful to you too.
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