NSBlog

Friday Q&A 2013-06-14: Reachability

Mike Ash — Fri, 14 Jun 2013 13:49:00 GMT

Networking is playing an ever more important role in application development, and Apple's reachability API is a valuable tool in making network-centric apps play nicely with varying real-world conditions. Today I'm going to give an overview of the reachability API, what it does, and how to use it, a suggestion from reader Manuel Diaz.
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Friday Q&A 2013-05-31: C Quiz

Mike Ash — Fri, 31 May 2013 13:46:00 GMT

I thought I'd mix things up a bit today and give my readers a quiz. The C language is perhaps the most popular computer language in existence, but it's also quite odd, and because of that often poorly understood. I'd like to give you a quiz to see how much you know about some of the odd but useful corners of the language.
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Friday Q&A 2013-05-17: Let's Build stringWithFormat:

Mike Ash — Fri, 17 May 2013 14:40:00 GMT

Our long effort to rebuild Cocoa piece by piece continues. For today, reader Nate Heagy has suggested building NSString's stringWithFormat: method.
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Friday Q&A 2013-05-03: Proper Use of Asserts

Mike Ash — Fri, 03 May 2013 13:03:00 GMT

Asserts are a powerful tool for building quality code, but they're often poorly understood. Today, I want to discuss the various options for writing asserts in Cocoa apps and the best ways to use them, a topic suggested by reader Ed Wynne.
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Friday Q&A Is On Vacation

Mike Ash — Fri, 19 Apr 2013 14:24:00 GMT

Friday Q&A is on vacation at the moment, so there will be no article today. Never fear: although he's busy relaxing today, Friday Q&A will return, and soon. To keep my loyal readers from being too upset, here is a collection of links to interesting articles to keep you occupied.
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Friday Q&A 2013-04-05: Windows and Window Controllers

Mike Ash — Fri, 05 Apr 2013 13:36:00 GMT

It's time to take a turn to some lighter fare, but to a subject that's near and dear to my heart. The fundamental UI component of a Cocoa app is the NSWindow, and there are many different ways to instantiate and manage them, but there is only one correct way: for each type of window, there should be a separate nib file, and a specialized NSWindowController subclass. I'll walk through what this means and how to do it, a topic suggested by reader Mike Shields.
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Objective-C Literals in Serbo-Croatian

Mike Ash — Tue, 26 Mar 2013 23:48:00 GMT

Reader Anja Skrba from Webhostinggeeks.com has translated my Objective-C Literals article into Serbo-Croatian. It's always fun to see translations of my writing, even when I can't understand them at all. If you do understand Serbo-Croatian, or know someone who does, check it out. The Serbo-Croatian version of Objective-C Literals is available on Webhostinggeeks.com.
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Friday Q&A 2013-03-22: Let's Build NSInvocation, Part II

Mike Ash — Fri, 22 Mar 2013 14:57:00 GMT

Last time on Friday Q&A, I began the reimplementation of parts of NSInvocation as MAInvocation. In that article, I discussed the basic theory, the architecture calling conventions, and presented the assembly language glue code needed for the implementation. Today, I present the Objective-C part of MAInvocation.
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Friday Q&A 2013-03-08: Let's Build NSInvocation, Part I

Mike Ash — Fri, 08 Mar 2013 14:33:00 GMT

It's time for another trip into the nether regions of the soul. Reader Robby Walker suggested an article about NSInvocation, and I have obliged, implementing it from scratch for your amusement. Today I'll start on a guided tour down the hall of horrors that is MAInvocation, my reimplementation of the NSInvocation API. It's a big project, so today I'm going to focus on the basic principles and the assembly language glue code, with the rest of the implementation to follow.
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Friday Q&A 2013-02-22: Let's Build UITableView

Matthew Elton — Fri, 22 Feb 2013 15:35:00 GMT

Friday Q&A is driven by the readers, and that's especially true today. Reader Matthew Elton thought that "Let's Build UITableView" would make a good topic for Friday Q&A, but he decided he'd rather implement it himself and write it up rather than wait for me to do it (good move, Matthew). Without further ado, here is Matthew's article an building UITableView.
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Friday Q&A 2013-02-08: Let's Build Key-Value Coding

Mike Ash — Fri, 08 Feb 2013 14:17:00 GMT

Last time, I showed how to build the basic functionality of NSObject. I left out key-value coding, because the implementation of valueForKey: and setValue:forKey: is complex enough to need its own article. This is that article.
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Friday Q&A 2013-01-25: Let's Build NSObject

Mike Ash — Fri, 25 Jan 2013 15:32:00 GMT

The NSObject class lies at the root of (almost) all classes we build and use as part of Cocoa programming. What does it actually do, though, and how does it do it? Today, I'm going to rebuild NSObject from scratch, as suggested by friend of the blog and occasional guest author Gwynne Raskind.
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Friday Q&A 2013-01-11: Mach Exception Handlers

Landon Fuller — Fri, 11 Jan 2013 14:44:00 GMT

This is my first guest Friday Q&A article, dear readers, and I hope it will withstand your scrutiny. Today's topic is on Mach exception handlers, something I've recently spent some time exploring on Mac OS X and iOS for the purpose of crash reporting. While there is surprisingly little documentation available about Mach exception handlers, and they're considered by some to be a mystical source of mystery and power, the fact is that they're actually pretty simple to understand at a high level - something I hope to elucidate here. Unfortunately, they're also partially private API on iOS, despite being used in a number of new crash reporting solutions - something I'll touch on in the conclusion.
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Friday Q&A 2012-12-28: What Happens When You Load a Byte of Memory

Mike Ash — Fri, 28 Dec 2012 14:45:00 GMT

The hardware and software that our apps run on is almost frighteningly complicated, and there's no better place to see that than in the contortions that the system goes through when we load data from memory. What exactly happens when we load a byte of memory? Reader and friend of the blog Guy English suggested I dedicate an article to answering that question.
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Friday Q&A 2012-12-14: Objective-C Pitfalls

Mike Ash — Fri, 14 Dec 2012 14:38:00 GMT

Objective-C is a powerful and extremely useful language, but it's also a bit dangerous. For today's article, my colleague Chris Denter suggested that I talk about pitfalls in Objective-C and Cocoa, inspired by Cay S. Horstmann's article on C++ pitfalls.
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Friday Q&A 2012-11-30: Let's Build A Mach-O Executable

Gwynne Raskind — Fri, 30 Nov 2012 17:59:00 GMT

This is something of a followup to my last article, dyld: Dynamic Linking On OS X, in which I explored how the dynamic linker dyld does its job. This week, I'm going to recreate the function of both the compiler and the static linker, building a Mach-O binary completely from scratch with only the help of the assembler.
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Friday Q&A 2012-11-16: Let's Build objc_msgSend

Mike Ash — Fri, 16 Nov 2012 14:27:00 GMT

The objc_msgSend function underlies everything we do in Objective-C. Gwynne Raskind, reader and occasional Friday Q&A guest contributor, suggested that I talk about how objc_msgSend works on the inside. What better way to understand how something works than to build it from scratch? Let's build objc_msgSend.
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Friday Q&A 2012-11-09: dyld: Dynamic Linking On OS X

Gwynne Raskind — Fri, 09 Nov 2012 15:51:00 GMT

In the course of a recent job interview, I had an opportunity to study some of the internals of dyld, the OS X dynamic linker. I found this particular corner of the system interesting, and I see a lot of people having trouble with linking issues, so I decided to do an article about the basics of dynamic linking. Some of the deeper logic is new to me, so sorry in advance for any inaccuracies.
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Friday Q&A 2012-11-02: Building the FFT

Chris Liscio — Fri, 02 Nov 2012 14:29:00 GMT

In the last post in this mini-series, Mike gave an overview of the Fourier Transform and then showed you how to use Apple's implementation of the Fast Fourier Transform (FFT).
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Friday Q&A 2012-10-26: Fourier Transforms and FFTs

Mike Ash — Fri, 26 Oct 2012 13:25:00 GMT

Last time around I discussed the basics of audio data, how to get it, and how to understand it. Today, I'm going to go into some detail about one of the fundamental tools for more complex audio analysis, the fourier transform, and the FFT algorithm that makes it practical to use on computers.
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