Question

My app needs to be compatible with different OS versions.

How do I detect if a specific class is available to use with the particular OS?

As an example, NSPopover is only available in Lion and up, so how can I check if the OS supports NSPopover in case the person is using Snow Leopard?

Answer 1

You could do

if ([TheWantedClass class]) {
    // The class exists so run code
} else {
    // The class doesn't exist so use an alternate approach
}

or

if (NSClassFromString(@"TheWantedClass") != nil) {
    // The class exists
} else {
    // The class doesn't exist
}

https://developer.apple.com/documentation/foundation/1395135-nsclassfromstring