added image2DataURL

README.md

+Parts are based on
+
+- https://github.com/ryouaki/Cordova-Plugin-Photos
+- https://github.com/subitolabs/cordova-gallery-api 

src/ios/PhotoLibrary.swift

@@ -39,6 +39,30 @@ import Foundation
     dateFormatter.dateFormat = "yyyy-MM-dd'T'HH:mm:ss.SSS"
   }
 
+    private func image2DataURL(image: UIImage) -> String? {
+        var imageData: NSData?
+        var mimeType: String
+        if (imageHasAlpha(image)){
+            imageData = UIImagePNGRepresentation(image)
+            mimeType = "image/png"
+        } else {
+            imageData = UIImageJPEGRepresentation(image, 1.0)
+            mimeType = "image/jpeg"
+        }
+        if (imageData != nil) {
+            let encodedString = imageData?.base64EncodedStringWithOptions(NSDataBase64EncodingOptions(rawValue: 0))
+            if (encodedString != nil) {
+                return String(format: "data:%@;base64,%@", mimeType, encodedString!)
+            }
+        }
+        return nil
+    }
+
+    private func imageHasAlpha(image: UIImage) -> Bool {
+        let alphaInfo = CGImageGetAlphaInfo(image.CGImage)
+        return alphaInfo == .First || alphaInfo == .Last || alphaInfo == .PremultipliedFirst || alphaInfo == .PremultipliedLast
+    }
+
   // Will sort by creation date
   func getPhotos(command: CDVInvokedUrlCommand) {
     dispatch_async(dispatch_get_main_queue(), {
@@ -66,7 +90,7 @@ import Foundation
                 resultImage["id"] = asset.localIdentifier
                 resultImage["filename"] = imageURL?.pathComponents?.last
                 resultImage["nativeUrl"] = imageURL?.absoluteString //TODO: in Swift 3, use JSONRepresentable
-                resultImage["url"] = nil //TODO: convert to data url
+                resultImage["url"] = image != nil ? self.image2DataURL(image!) : nil
                 resultImage["width"] = asset.pixelWidth
                 resultImage["height"] = asset.pixelHeight
                 resultImage["creationDate"] = self.dateFormatter.stringFromDate(asset.creationDate!) //TODO: in Swift 3, use JSONRepresentable