gistfile1.m

self.didDownload = [[NSMutableArray alloc] initWithCapacity:[self.wallpapers count]];
for (int  i = 0; i < [self.wallpapers count]; i++) {
        NSMutableArray *didDownloadPage = [[NSMutableArray alloc] initWithCapacity:2];
        [didDownloadPage insertObject:[NSNumber numberWithBool:NO] atIndex:IMG_TYPE_HOME];
        [didDownloadPage insertObject:[NSNumber numberWithBool:NO] atIndex:IMG_TYPE_LOCK];
        [self.didDownload insertObject:didDownloadPage atIndex:i];
}