Cocoa with Love

Custom views in Interface Builder using IBPlugins

Jul 2, 2009 (an Objective-C era article)

If you have custom views configured in code, it can be time consuming to configure them for each instance and make them look right in context. To make the process smoother, you can create Interface Builder plugins and configure your objects in Interface Builder. While the Xcode documentation explains how to do this, it is long, thorough and confusing. Here is the simplified set of steps that I use to create Interface Builder plugins quickly.

Read more...
Verifying that a string contains an email address using NSPredicate

Jun 23, 2009 (an Objective-C era article)

To celebrate the official release of iPhone OS 3.0 this week, I will show you how to verify that an NSString contains a syntactically valid email address using NSPredicate — a class that joins the iPhone SDK 3.0 as part of the Core Data additions. This code will work on Mac OS X too since, as with the rest of Core Data, NSPredicate has been part of Mac OS X since 10.4 (Tiger).

Read more...
Revisiting an old post: Streaming and playing an MP3 stream

Jun 17, 2009 (an Objective-C era article)

Given the attention it received and the number of bugs I know it contained, I wanted to revisit an old post of mine: Streaming and playing an MP3 stream. In this post, I'll talk about the problems the original contained, how I fixed those problems and I'll present the updated result.

Read more...
Method names in Objective-C

Jun 10, 2009 (an Objective-C era article)

Compared to other languages, method names in Objective-C are weird. They're long, they're wordy, they include names for the parameters and they seem to repeat information you can get elsewhere. Despite these apparent negatives, Objective-C method naming can save you time and effort. I'll show you how methods are named so that you can predict them without documentation and understand how methods work and how they use their parameters from their names alone.

Read more...
Base64 encoding options on the Mac and iPhone

Jun 3, 2009 (an Objective-C era article)

On Unix platforms, a common approach for Base64 encoding is to use libcrypto (the OpenSSL library). However, like most C libraries, you need to wrap it to integrate with Objective-C data types (like NSData and NSString) and it isn't available on the iPhone. I'll show you how to handle base64 encoding/decoding with OpenSSL and without so you can handle the Mac and iPhone equally.

Read more...
Simple methods for date formatting and transcoding

May 25, 2009 (an Objective-C era article)

There is no single-line method for converting between formatting date strings and date objects in Cocoa — the API opts for flexibility rather than simplicity. Unfortunately, this combines with documentation that omits, misdirects and occasionally misinforms, making NSDateFormatter one of the more confusing classes for new Cocoa programmers. In this post, I'll try to address some of the documentation issues and I'll present some methods that will turn NSDate into a formatted string or convert between date strings in a single method.

Read more...
Intercepting status bar touches on the iPhone

May 19, 2009 (an Objective-C era article)

You can configure your iPhone applications so that a touch in the status bar will scroll a UIScrollView to the top. I'll show you how you can intercept this touch event to use status bar touches for other purposes. The sample application will show a hidden drawer that slides out from the status bar when you tap it.

Read more...
Variable argument lists in Cocoa

May 10, 2009 (an Objective-C era article)

This week I'll talk about methods that take variable numbers of arguments, also known as variadic methods. I'll show you the Objective-C syntax and implementation, give a quick rundown of the ways that Cocoa classes provide variable argument support and I'll also show you a way to fake va_list parameters to handle Cocoa's variadic method equivalents at runtime.

Read more...
Invoking other processes in Cocoa

May 4, 2009 (an Objective-C era article)

Invoking other processes is a good way to handle some low-level tasks on the Mac. I'll show you some simple ways to invoke processes and parse their outputs in Cocoa apps as well as some advanced tricks like running a process with administrator privileges.

Read more...
Easy custom UITableView drawing

Apr 28, 2009 (an Objective-C era article)

It is really easy to customize your UITableViews. I'll show you how to completely customize the appearance of UITableViews without overriding or subclassing and without the need for any tricky hackery.

Read more...