Cordova File-Transfer download fails on iOS

function win(entry){
    console.log("OK!");
}

function fail(error){
    console.log("ERROR!");
    console.log(error.code);
}


var url = "http://upload.wikimedia.org/wikipedia/commons/5/5b/Ultraviolet_image_of_the_Cygnus_Loop_Nebula_crop.jpg";

var filename = "filename.jpg";


var uri = encodeURI(url);
window.requestFileSystem(LocalFileSystem.PERSISTENT, 0, function(fileSystem) {
       fileSystem.root.getFile(filename, {create: true, exclusive: false}, function(fileEntry) {
           var localPath = fileEntry.toURL();
           var ft = new FileTransfer();
           ft.download(uri,localPath,win,fail,false);

       },function(error){console.log("errore 1: " + error.code);});
    },function(error){console.log("errore 2: " + error.code);});