Finally I'd figure it out like this,
label.text = [label.text stringByReplacingOccurrencesOfString:@"Ã" withString:@"à"];
I got to know, some problems really don't need big attention or answer. I know this is a patch and not the proper way but helpful and time saver for now. Thanks everyone who've attended. :)
I'm still looking for some wide solution for such kind of conversation.