Using key-value programming (KVP) with Swift

Question

In Objective-C with Cocoa a lot of tasks can be accomplished without explicit loops by using Key-Value Programming (KVP). For example, I can find the largest number in an array

Answer 1

The array will actually respond to valueForKeyPath function - you just need to cast the array to AnyObject so that the compiler doesn't complain. As follows:

var max = (numbers as AnyObject).valueForKeyPath("@max.self") as Double

or even, for a union of objects:

(labels as AnyObject).valueForKeyPath("@unionOfObjects.text")

If labels above is a collection of labels, the above will return an array of all the strings of the text property of each label.

It is also equivalent to the following:

(labels as AnyObject).valueForKey("text")

... just as it is in Objective-C :)