func getTumbnails(imageName: String) {
    // Create a reference to the file you want to download
    let tumbnailRef = storageRef.child("tumbs/(imageName)")
    // Create local filesystem URL
    let localURL: NSURL! = NSURL(string: "file:///local/tumbnails/(imageName)")

    // Download to the local filesystem
    let downloadTask = tumbnailRef.writeToFile(localURL) { (URL, error) -> Void in
        if (error != nil) {
            print(error)
        } else {
            let data = NSData(contentsOfURL: URL!)
            self.data = data!
            print(data)
        }
    }
}