hollance

Communicate between objects using channels

When you have two objects A and B, say two view controllers, that you want to have talk to each other, you can choose from the following options:

• NSNotificationCenter. This is anonymous one-to-many communication. Object A posts a notification to the NSNotificationCenter, which then distributes it to any other objects listening for that notification, including Object B. A and B do not have to know anything about each other, so this is a very loose coupling. Maybe a little too loose...

• KVO (Key-Value Observing). One object observes the properties of another. This is a very tight coupling, because Object B is now peeking directly into Object A. The advantage of KVO is that Object A doesn't have to be aware of this at all, and therefore does not need to send out any notifications -- the KVO mechanism takes care of this behind the scenes.

• Direct pointers. Object A has a pointer to Object B and directly sends it messages when something of interest h

avdwerff

extension Array where Element: Comparable {
    
    func mergeSort() -> [Element] {
        if count <= 1 { return self }
        else {
            let left = Array(self[0 ..< count/2])
            let right = Array(self[count/2 ..< count])
            return merge(left.mergeSort(), right: right.mergeSort())
        }
    }