Swift2从Firebase检索图像

Question

I am trying to read/display an image from Firebase. I am first encoding the image and then posting this encoded String to Firebase. This runs fine. When I try and decode the encoded string from Firebase and convert it to an image, I am getting a nil value exception.

This is how I am saving the image to Firebase

var base64String: NSString!
func imagePickerController(picker: UIImagePickerController, didFinishPickingImage image: UIImage, editingInfo: [String : AnyObject]?) {

    self.dismissViewControllerAnimated(true, completion: nil)

    imageToPost.image = image

    var uploadImage = image as! UIImage
    var imageData = UIImagePNGRepresentation(uploadImage)!
    self.base64String = imageData.base64EncodedStringWithOptions(NSDataBase64EncodingOptions.Encoding64CharacterLineLength)
    let ref = Firebase(url: "https://XXX.firebaseio.com")

    var quoteString = ["string": self.base64String]
    var usersRef = ref.childByAppendingPath("goalImages")
    var users = ["image": quoteString]
    usersRef.setValue(users)

    displayAlert("Image Posted", message: "Your image has been successfully posted!")
}

This is how I am trying to read the image from Firebase

//  ViewController.swift

import UIKit
import Firebase

class ViewController: UIViewController {
@IBOutlet weak var image: UIImageView!
var base64String: NSString!

@IBAction func buttonClicked(sender: AnyObject) {

    sender.setTitle("\(sender.tag)", forState: UIControlState.Normal)

}

override func viewDidLoad() {
    super.viewDidLoad()
    // Do any additional setup after loading the view, typically from a nib.

    let ref = Firebase(url: "https://XXX.firebaseio.com/goalImages/image/string")

    ref.observeEventType(.Value, withBlock: { snapshot in

        self.base64String = snapshot.value as! NSString
        let decodedData = NSData(base64EncodedString: self.base64String as String, options: NSDataBase64DecodingOptions())
        //Next line is giving the error
        var decodedImage = UIImage(data: decodedData!)

        self.image.image = decodedImage
        }, withCancelBlock: { error in
            print(error.description)
        })

}

override func didReceiveMemoryWarning() {
    super.didReceiveMemoryWarning()
    // Dispose of any resources that can be recreated.
}
}

The error says: "fatal error: unexpectedly found nil while unwrapping an Optional value"; decodedData is nil. Could someone explain what is going wrong.

Answer 1

Instead of

let decodedData = NSData(base64EncodedString: self.base64String as String, 
                                     options: NSDataBase64DecodingOptions())

try adding IgnoreUnknownCharacters

NSDataBase64DecodingOptions.IgnoreUnknownCharacters

Use Example: Encode a jpg, store and read from firebase

encode and write our favorite starship

    if let image = NSImage(named:"Enterprise.jpeg") {
    let imageData = image.TIFFRepresentation
    let base64String = imageData!.base64EncodedStringWithOptions(.Encoding64CharacterLineLength)
    let imageRef = myRootRef.childByAppendingPath("image_path")
    imageRef.setValue(base64String)

read and decode

       imageRef.observeEventType(.Value, withBlock: { snapshot in

            let base64EncodedString = snapshot.value
            let imageData = NSData(base64EncodedString: base64EncodedString as! String, 
                           options: NSDataBase64DecodingOptions.IgnoreUnknownCharacters)
            let decodedImage = NSImage(data:imageData!)
            self.myImageView.image = decodedImage

            }, withCancelBlock: { error in
                print(error.description)
        })

EDIT 2019_05_17

Update to Swift 5 and Firebase 6

func writeImage() {
    if let image = NSImage(named:"Enterprise.jpg") {
        let imageData = image.tiffRepresentation
        if let base64String = imageData?.base64EncodedString() {
            let imageRef = self.ref.child("image_path")
            imageRef.setValue(base64String)
        }
    }
}

func readImage() {
    let imageRef = self.ref.child("image_path")
    imageRef.observeSingleEvent(of: .value, with: { snapshot in
        let base64EncodedString = snapshot.value as! String
        let imageData = Data(base64Encoded: base64EncodedString, options: Data.Base64DecodingOptions.ignoreUnknownCharacters)!
        let decodedImage = NSImage(data: imageData)
        self.myImageView.image = decodedImage
    })
}

Answer 2

Firebase Engineer here:

I highly recommend using the new Firebase Storage API for uploading images to Firebase. It's simple to use, low cost, and backed by Google Cloud Storage for huge scale.

You can upload from NSData or an NSURL pointing to a local file (I'll show NSData , but the principle is the same):

// Data in memory
let data: NSData = ...

// Create a reference to the file you want to upload
let riversRef = storageRef.child("images/rivers.jpg")

// Upload the file to the path "images/rivers.jpg"
let uploadTask = riversRef.putData(data, metadata: nil) { metadata, error in
  if (error != nil) {
    // Uh-oh, an error occurred!
  } else {
    // Metadata contains file metadata such as size, content-type, and download URL.
    let downloadURL = metadata!.downloadURL
    // This can be stored in the Firebase Realtime Database
    // It can also be used by image loading libraries like SDWebImage
  }
}

You can even pause and resume uploads, and you can easily monitor uploads for progress:

// Upload data
let uploadTask = storageRef.putData(...)

// Add a progress observer to an upload task
uploadTask.observeStatus(.Progress) { snapshot in
  // Upload reported progress
  if let progress = snapshot.progress {
    let percentComplete = 100.0 * Double(progress.completedUnitCount) / Double(progress.totalUnitCount)
  }
}