Im new to objective-c
Lets assume I have a string such as this 

`NSString* s = @"assets-library://asset/asset.MOV? id=100000009&amp;ext=MOV"`

how do I get the contents of the "ext=" ("MOV" in this case) out of it? How do I convert it to uppercase(so "mov" -> "MOV") in case it is not already so?