unable to download all songs from server

in my app i am having a button called download all clicking on which i have to download all songs present on my server. i am able to download one song at a time. Be开发者_JAVA百科low is my code:

NetworkManager *manager = [[NetworkManager alloc] init];

NSString *Mp3filePath = [manager GetFile:SongUrl];



NSLog(@"aaaaa");


SongUrl= [[NSString alloc] initWithString:@"my URL"];

NSLog(@"aaaaa");



NSLog(@"songurl--%@",SongUrl);

steps to consider:

1. Download a list of songs
2. Compose this list of songs into URLs (if they aren't already)
3. Iterate over the list of songs, downloading them one by one.
4. If process is interrupted (network lost or user cancel), record what you have downloaded, so you can resume again.