[MulticastDelegate] #swift Utility Class that can hold on to any number of delegates and invoke arbitrary blocks of code on them

MulticastDelegate.swift

/// Utility Class that can hold on to any number of delegates and invoke arbitrary blocks of code on them
public class MulticastDelegate<T: AnyObject> {
    /// HashTable containing any number of delegates, held weakly
    private let delegates: NSHashTable<AnyObject> = NSHashTable.weakObjects()

    /// Adds delegate to list of delegates
    ///
    /// - Parameter delegate: Delegate to add to list of known delegates
    public func add(_ delegate: T) {
        delegates.add(delegate as AnyObject)
    }

    /// Removes last known delegate from list of delegates
    ///
    /// - Parameter delegate: Delegate to remove from list
    public func remove(delegate: T) {
        for d in delegates.allObjects.reversed() {
            if d === delegate  as AnyObject {
                delegates.remove(d)
            }
        }
    }

    /// Invokes closures on each of the known delegates
    ///
    /// - Parameter invocation: Closure containing code
    public func invoke(_ invocation: (T) -> Void) {
        for delegate in delegates.allObjects.reversed() {
            invocation(delegate as! T)
        }
    }
}