Objective-C Language is used to create Iphone apps. Iphone uses IOS as it's operating system.
Objective-C is the primary programming language you use when writing software for OS X and iOS.
It’s a superset of the C programming language and provides object-oriented capabilities and a dynamic runtime. Objective-C inherits the syntax, primitive types, and flow control statements of C and adds syntax for defining classes and methods. It also adds language-level support for object graph management and object literals while providing dynamic typing and binding, deferring many responsibilities until runtime.
There are many tutorial available online for beginning with IOS developement center
Official IOS development
you can get help from this nice book too