Learn C on the Mac: For OS X and iOS, Second Edition is perfect for beginners learning to program. It includes contemporary OS X and iOS examples! This book also does the following:

•  Provides best practices for programming newbies 

•  Presents all the basics with a pragmatic, Mac OS X and iOS -flavored approach

•  Includes updated source code which is fully compatible with latest Xcode

After reading this book, you'll be ready to program and build apps using the C language and Objective-C will become much easier for you to learn when you're ready to pick that up.