Generic NSCache in Swift

Cache.swift

import Foundation

class Cache<T: AnyObject>: NSCache {
    
    subscript(key: AnyObject) -> T? {
        get {
            return objectForKey(key)
        }
        set {
            if let value = newValue {
                setObject(value, forKey: key)
            } else {
                removeObjectForKey(key)
            }
        }
    }
    
    func objectForKey(key: AnyObject) -> T? {
        return super.objectForKey(key) as? T
    }
    
}