Encapsulating displaying a HUD (and its implementation)

HUDOperation.swift

enum HUDAppearanceMode {
    case Indeterminate
    case IndeterminateWithStatus(status: String)
}

enum HUDDismissalMode {
    case Immediately
    case WithDelay(delay: NSTimeInterval)
    case WithStatus(successStatus: String, failureStatus: String)
}

class HUDOperationObserver: OperationDidStartObserver, OperationDidCancelObserver, OperationDidFinishObserver {
    var appearanceMode: HUDAppearanceMode = .Indeterminate
    var dismissalMode: HUDDismissalMode = .Immediately
    
    init(appearanceMode: HUDAppearanceMode, dismissalMode: HUDDismissalMode) {
        self.appearanceMode = appearanceMode
        self.dismissalMode = dismissalMode
    }
    
    convenience init(appearanceMode: HUDAppearanceMode) {
        self.init(appearanceMode: appearanceMode, dismissalMode: .Immediately)
    }
    
    func didStartOperation(operation: Operation) {
        switch appearanceMode {
        case .Indeterminate:
            SVProgressHUD.show()
        case .IndeterminateWithStatus(let status):
            SVProgressHUD.showWithStatus(status)
        }
    }
    
    func didCancelOperation(operation: Operation) {
        switch dismissalMode {
        case .Immediately:
            SVProgressHUD.dismiss()
        case .WithDelay(let delay):
            SVProgressHUD.dismissWithDelay(delay)
        default:
            SVProgressHUD.dismiss()
        }
    }
    
    func didFinishOperation(operation: Operation, errors: [ErrorType]) {
        switch dismissalMode {
        case .Immediately:
            SVProgressHUD.dismiss()
        case .WithDelay(let delay):
            SVProgressHUD.dismissWithDelay(delay)
        case .WithStatus(let successStatus, let failureStatus):
            if errors.count > 0 {
                SVProgressHUD.showErrorWithStatus(failureStatus)
            }
            else {
                SVProgressHUD.showSuccessWithStatus(successStatus)
            }
        }
    }
    
}

HUDOperationExample.swift

// I like this for several reasons:
// 1. Showing/Hiding a HUD during an operation is 1-2 lines of code
// 2. Simple API, builds on top of the observer pattern
// 3. HUD implementation (or library, SVProgressHUD in my case) is encapsulated and easily changed

let uploadOperation = UploadOperation(networkController: AlamoNetworkController.sharedInstance!, image: image)

imageUploadOperation.addObserver(HUDOperationObserver(
    appearanceMode: .IndeterminateWithStatus(status: "Uploading..."),
     dismissalMode: .WithStatus(successStatus: "Upload Complete", failureStatus: "Upload Failed")
))

imageUploadOperation.addObserver(DidFinishObserver() { _, _ in
    self.dismissViewControllerAnimated(true, completion: nil)
})

operationQueue.addOperation(uploadOperation)