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Storage for Pages (SBSDKIndexedImageStorage, SBSDKKeyedImageStorage)

The document pages display the scanned images, and these images can be stored using SBSDKIndexedImageStorage or SBSDKKeyedImageStorage.

  • SBSDKIndexedImageStorage and SBSDKKeyedImageStorage are thread-safe and persistent storages for images.
  • They can be used to store and retrieve images in an array-fashioned style (indexed) or dictionary-fashioned style (keyed) to and from the device disk.
  • Both allow the usage of an encrypter which encrypts the data when writing it to the disk and decrypts the data when reading it from the disk.
  • These classes conform to the SBSDKImageStoring protocol. Custom image storages can be implemented and used within Scanbot SDK by conforming to this protocol.
import UIKit
import ScanbotSDK

class ImageStoringSwiftViewController: UIViewController {

override func viewDidLoad() {
super.viewDidLoad()

// Initialize a folder URL to persist the images to.
let documentsURL = SBSDKStorageLocation.applicationDocumentsFolderURL.appendingPathComponent("Images", isDirectory: true)

// Create a storage location object. This will create the folder on the filesystem if neccessary.
let documentsLocation = SBSDKStorageLocation(baseURL: documentsURL)

// Initialize an indexed image storage at this location.
// The indexed image storage is an array-like storage.
let imageStorage = SBSDKIndexedImageStorage(storageLocation: documentsLocation,
fileFormat: .PNG,
encrypter: nil)!

if let image = UIImage(named: "testDocument") {
// Save an image to the storage.
let isAdded = imageStorage.add(image)
// Check the result.
print("Image added successfully: \(isAdded)")
}
// Check the number of images in the storage.
print("Images in storage: \(imageStorage.imageCount)")


// Create and attach an encrypter to the storage. This will encrypt the image data, before it is written to disk
// and decrypt it after it is read from disk.
// Setting the encrypter does not encrypt existing images in the storage, only the images that are added to the
// storage after setting the encrypter.
imageStorage.encrypter = SBSDKAESEncrypter(password: "xxxxx", mode: .AES256)

// Store an image from a URL. This does not load the image and has a very low memory footprint.
if let url = Bundle.main.url(forResource: "imageDocument", withExtension: "png") {
// Copy the image from the URL to the storage.
let isAdded = imageStorage.addImage(from: url)
// Check the result.
print("Image from URL was added successfully : \(isAdded)")
}

// Make sure that the indices are valid before moving an image from one index to another.
if imageStorage.imageCount > 1 {
// Move the image at index 1 to index 0.
let isMoved = imageStorage.moveImage(from: 1, to: 0)
print("Image was moved successfully: \(isMoved)")
}

// Make sure that the index is valid.
if imageStorage.imageCount > 1 {
// Remove the image at index 1.
imageStorage.removeImage(at: 1)
}

// The image storage is persisted on disk.
// When the images are no longer needed they should be removed to free the disk space.
// Remove all images from the storage.
imageStorage.removeAll()
}
}

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