// Option 1: if..elseif + optional unwrapping conditions

private func handleNotificationAction(id: String?, userInfo: [NSObject: AnyObject], responseInfo: [NSObject: AnyObject]?, completion: () -> Void) {
    let taskId = userInfo["extra"]?["task_hash"] as? String
    let projectId = userInfo["extra"]?["project_hash"] as? String
    let comment = responseInfo?["UIUserNotificationActionResponseTypedTextKey"] as? String

    if id == "comment", let task = taskId, comment = comment where !comment.isEmpty {

    } else if id == "invitation_accept", let project = projectId {

    } else if id == "invitation_decline", let project = projectId {

    } else if id == "star", let task = taskId {

    } else if id == "complete", let task = taskId {

    } else if id == "show" || id == "comment" || id == "delegate", let task = taskId {

    } else {
        // assertionFailure
    }
}

// Option 2: switch + force unwrap

private func handleNotificationAction(id: String?, userInfo: [NSObject: AnyObject], responseInfo: [NSObject: AnyObject]?, completion: () -> Void) {
    let taskId = userInfo["extra"]?["task_hash"] as? String
    let projectId = userInfo["extra"]?["project_hash"] as? String
    let comment = responseInfo?["UIUserNotificationActionResponseTypedTextKey"] as? String

    switch id {
    case "comment"? where taskId != nil && comment != nil && !comment.isEmpty:

    case "invitation_accept"? where projectId != nil:

    case "invitation_decline"? where projectId != nil:

    case "star"? where taskId != nil:

    case "complete"? where taskId != nil:

    case "show"?, "comment"?, "delegate"? where taskId != nil:

    default:
        // assertionFailure
    }
}