Which language to choose?

Hi, im new to this forum and is seeking help whether to choose iOS over server side languages like Python, Ruby, Java, .NET, PHP. I know there is a proliferating demand for iOS developers though the demand for server languages has been high. I am confused whether to choose iOS or any other language. Being a beginner which one would you advise me to go for. I am really interested in programming and im trying out some stuff on my own. I am graduating out of high school next year and looking for a career in app development. I recently came to know about mobile app development course in Toronto that is career oriented. I am planning to join the course next year but still not decided. Looking for advice from experts in programming. Thank you!