         networkActivityIndicator = indicator
     }
 
+    /// Conforms to `OperationObserver`, will start the network activity indicator.
     public func operationDidStart(operation: Operation) {
         dispatch_async(Queue.Main.queue) {
             NetworkIndicatorController.sharedInstance.networkActivityIndicator = self.networkActivityIndicator

        }
    }

    public func operation(operation: Operation, didProduceOperation newOperation: NSOperation) {
        // no-op
    }

    public func operationDidFinish(operation: Operation, errors: [ErrorType]) {
        dispatch_async(Queue.Main.queue) {
            NetworkIndicatorController.sharedInstance.networkActivityIndicator = self.networkActivityIndicator


import UIKit

protocol NetworkActivityIndicatorInterface {
    var networkActivityIndicatorVisible: Bool { get set }
}

