File Transfer Download work in IOS emulation but not work in IOS Device

Hi
i use Native File Transfer for Downloading Files from Wordpress. its work like charm in android BUT in IOS not work
i use xcode for emulate and Build app in Mac. when i test app in simulation of xcode File Transfer Work but when Build App for IOS its not working (other things work).
also i test other storage place like appdirectory and … reference and remove and reinstall file transfer plugin but not solve the problem

download.ts
(download is a component not page)

download_song() {
        this.plt.ready().then(() => {
            let path = null;
            if (this.plt.is('ios')) {
                path = this.file.cacheDirectory;
            } else if (this.plt.is('android')) {
                path = this.file.externalDataDirectory;
            }
            if (this.playlist_select!=null && this.playlist_select!= undefined ) {
                    this.is_download = true;
                    this.file_transfer = this.transfer.create();
                    this.file_transfer.download(this.select_url, path + this.post.id + '.mp3').then((entry) => {
                        this.download_song_addList();
                    }, (error) => {
                        this.viewCtrl.dismiss();
                    });
                    this.img_transfer = this.transfer.create();
                    this.img_transfer.download(this.post.img, path + this.post.id + '.jpg').then((entry) => {
                    }, (error) => {

                    });
                    this.file_transfer.onProgress((progressEvent) => {
                        this._zone.run(() => {
                            this.dl_loaded = this.formatBytes(progressEvent.loaded);
                            this.dl_total = this.formatBytes(progressEvent.total);
                            this.dl_total_byet = progressEvent.total;
                            this.dl_loaded_byet = progressEvent.loaded;
                            if (progressEvent.lengthComputable) {
                                var perc = Math.floor(progressEvent.loaded / progressEvent.total * 100);
                            }
                        });
                    });
            }else {
                this.presentPrompt();
            }
        });
    }

also i use safari to debug and find error but in simulation isn’t any error.

My Project Info :

Thanks.