Instagram can only share photo & video, so please check the “itemsArray” only include photo & video otherwise you will not see the instagram icon in UIActivityViewController.
NSURL *videoURL = [NSURL URLWithString:self.combineFilePath];
NSArray *itemsArray = [[NSArray alloc] initWithObjects:videoURL, nil];
UIActivityViewController *controller = [[UIActivityViewController alloc] initWithActivityItems:itemsArray applicationActivities:nil];