A simple implementation of Observables in Swift

Observables.swift

struct Observable<T> {
    
    typealias Observer = (send:(newValue: T) -> ())
    
    var observers = Dictionary<String, Observer>()
    
    var value: T {
        didSet {
            _notify()
        }
    }
    
    /**
    *  Create a new Observable with a stored value
    */
    init(_ value: T) {
        self.value = value
    }
    
    /**
    *  Get the value stored instide the `Observable`.
    *
    *  @return The value stored inside the observer.
    */
    func get() -> T {
        return value
    }
    
    /**
    *  Update the stored value of the `Observable` and notify the observers.
    *
    *  @param value A new value of type T
    */
    mutating func set(value: T) {
        self.value = value
    }

    /**
    *  Add an observer with a random identifier
    *
    *  @param observer A closure that takes a paramater of type T
    *
    *  @return The identifier of the observer
    */
    mutating func addObserver(observer: Observer) -> String {
        var identifier = _randomIdentifier()
        addObserver(identifier, observer: observer)
        
        return identifier
    }
    
    /**
    *  Add an observer with a given identifier
    *
    *  @param identifier The identifier to register an observer for
    *  @param observer A closure that takes a paramater of type T
    */
    mutating func addObserver(identifier: String, observer: Observer) {
        observers[identifier] = observer
    }
    
    /**
    *  Remove an Observer with a given identifier
    *
    *  @param identifier the Observer to remove an identifier for
    */
    mutating func removeObserver(identifer: String) {
        observers.removeValueForKey(identifer)
    }
    
    // Private
    
    func _notify() {
        for (identifier, observer) in observers {
            observer.send(newValue: value)
        }
    }
    
    func _randomIdentifier() -> String {
        var tempString = ""
        for index in (0 ..< 30) {
            tempString += String(arc4random_uniform(10))
        }
        
        return tempString
    }
}