What is the Best Way to Use iPhone 3.0 Features While Still Maintaining Compatibility with Earlier Versions?

Question

For example, suppose I had written my own class which allowed me to record audio on the iPhone. iPhone OS 3.0 now provides that functionality as a part of the Cocoa Touch Framework.

How can I use my existing class to support iPhone OS version 2.2.1 and earlier, but at the same time take advantage of the new class provided by the Cocoa Touch Framework to support iPhone OS 3.0?

Answer 1

Since Objective-C is a very dynamic language, you can target 2.x and query for the existence of 3.0 features:

id pasteboard = [objc_getClass("UIPasteboard") generalPasteboard];
if (pasteboard) {
    NSLog(@"Got pasteboard, we're clearly on 3.0+");
} else {
    NSLog(@"Pasteboard not available, definitely 2.x");
}