ionic FileTransfer下载目录为null

Question

我正在尝试检查inAppBrowser插件随附的下载。但是它不会下载文件。

const browser = inAppBrowser.create(url,'_self',options);

browser.on('loadstart').subscribe(event => {


let path = file.dataDirectory;

if(event.url.substring(8,11)=="doc"){
const transferF=transfer.create();
transferF.download(encodeURI(event.url),path+"file.pdf").then(indirme =>{
alertCtrl.create({
      title: 'indirme Tamam',
      subTitle: indirme.url,
      buttons: ['OK']
    }).present();
	
}). catch(error => {
alertCtrl.create({
      title: 'Hata',
      subTitle: 'Hata: '+error.exception,
      buttons: ['OK']
    }).present();

 })

}}, err=> {
	console.log(err);
});

警报 标题：Indirme tamam subtitle：indirme.url //indirme.url为空