Save UIImage array to disk - swift

Question

I have a UIImage array that I'm trying to save to disk (documents directory). I've converted it to Data so it can be saved but I can't figure out the correct/best way to save that [Data] to disk.
(arrayData as NSArray).write(to: filename, atomically: false) doesn't seem right or there seems like there is some better way.
Code so far:
// Get the new UIImage
let image4 = chartView.snapShot()
// Make UIImage into Data to save
let data = UIImagePNGRepresentation(image4!)
// Add Data image to Data Array
arrayData.append(data!)
// Get Disk/Folder
let filename = getDocumentsDirectory().appendingPathComponent("images")
// This is how I'd Write Data image to Disk
// try? data?.write(to: filename)
// TODO: Write array Data images to Disk
(arrayData as NSArray).write(to: filename, atomically: false)

Answer 1

To save your images to the document directory, you could start by creating a function to save your image as follows. The function handles creating the image name for you and returns it.
func saveImage(image: UIImage) -> String {
let imageData = NSData(data: UIImagePNGRepresentation(image)!)
let paths = NSSearchPathForDirectoriesInDomains(FileManager.SearchPathDirectory.documentDirectory, FileManager.SearchPathDomainMask.userDomainMask, true)
let docs = paths[0] as NSString
let uuid = NSUUID().uuidString + ".png"
let fullPath = docs.appendingPathComponent(uuid)
_ = imageData.write(toFile: fullPath, atomically: true)
return uuid
}
Now since you want to save an array of images, you can simply loop and call the saveImage function:
for image in images {
saveImage(image: image)
}
If you prefer to name those images yourself, you can amend the first function to the following:
func saveImage(image: UIImage, withName name: String) {
let imageData = NSData(data: UIImagePNGRepresentation(image)!)
let paths = NSSearchPathForDirectoriesInDomains(FileManager.SearchPathDirectory.documentDirectory, FileManager.SearchPathDomainMask.userDomainMask, true)
let docs = paths[0] as NSString
let name = name
let fullPath = docs.appendingPathComponent(name)
_ = imageData.write(toFile: fullPath, atomically: true)
}
When you save an image as a UIImagePNGRepresentation as you are trying to do, please note that is does not save orientation for you. This means that when you attempt to retrieve the image, it might be titled to the left. You will need to redraw your image to make sure it has the right orientation as this post will explain how to save png correctly. However, if you save your image with UIImageJPEGRepresentation you will not have to worry about all that and you can simply save your image without any extra effort.
EDITED TO GIVE ARRAY OF IMAGES
To retrieve the images you have saved, you can use the following function where you pass an array of the image names and you get an array back:
func getImage(imageNames: [String]) -> [UIImage] {
var savedImages: [UIImage] = [UIImage]()
for imageName in imageNames {
if let imagePath = getFilePath(fileName: imageName) {
savedImage.append(UIImage(contentsOfFile: imagePath))
}
}
return savedImages
}
Which relies on this function to work:
func getFilePath(fileName: String) -> String? {
let nsDocumentDirectory = FileManager.SearchPathDirectory.documentDirectory
let nsUserDomainMask = FileManager.SearchPathDomainMask.userDomainMask
var filePath: String?
let paths = NSSearchPathForDirectoriesInDomains(nsDocumentDirectory, nsUserDomainMask, true)
if paths.count > 0 {
let dirPath = paths[0] as NSString
filePath = dirPath.appendingPathComponent(fileName)
}
else {
filePath = nil
}
return filePath
}

Answer 2

You can below code to stored image into local.
let fileManager = NSFileManager.defaultManager()
let paths = (NSSearchPathForDirectoriesInDomains(.DocumentDirectory, .UserDomainMask, true)[0] as NSString).stringByAppendingPathComponent("ImageName.png")
let image = YOUR_IMAGE_TO_STORE.
let imageData = UIImageJPEGRepresentation(image!, 0.5)
fileManager.createFileAtPath(paths as String, contents: imageData, attributes: nil)