Cocoa with Love

Jul 23, 2009

Objective-C era

Temporary files and folders in Cocoa

If you need to use temporary files in your application and you search the Cocoa documentation for "temporary file", you're unlikely to find anything that explains how to create one. Since temporary files and folders are subject to a number of security issues and race conditions when done wrong, it is important to know the correct way to create them. I'll show you some code that you can copy and paste into your applications to create temporary files and folders safely.

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Jul 13, 2009

Objective-C era

A simple, extensible HTTP server in Cocoa

HTTP is one of the simpler protocols to implement for communication between computers. On the iPhone, since there are no APIs for data synchronization or file sharing, embedding an HTTP server is one of the best ways to transfer data from your iPhone application to a computer. In this post I'll show you how to write your own simple but extensible HTTP server. The server classes will also work on Mac OS X (Cocoa un-Touched).

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Jul 6, 2009

Objective-C era

HashValue: an object for holding MD5 and SHA hashes

Hash values are small, convenient values that you can generate from larger blocks of data for easy indexing, sorting and tracking. The traditional approach for generating MD5 and SHA hashes on Unix platforms to is to use command-line programs like openssl and md5. Apple provide easier approaches in the CommonCrypto library: here's how to use it, along with an NSValue subclass to wrap the result for interoperability with other Cocoa classes.

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Jul 2, 2009

Objective-C era

Custom views in Interface Builder using IBPlugins

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.

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Jun 23, 2009

Objective-C era

Verifying that a string contains an email address using NSPredicate

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).

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Jun 17, 2009

Objective-C era

Revisiting an old post: Streaming and playing an MP3 stream

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.

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Jun 10, 2009

Objective-C era

Method names in Objective-C

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.

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Jun 3, 2009

Objective-C era

Base64 encoding options on the Mac and iPhone

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.

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May 25, 2009

Objective-C era

Simple methods for date formatting and transcoding

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.

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May 19, 2009

Objective-C era

Intercepting status bar touches on the iPhone

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.

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