Although you can be successful in learning iOS programming without spending hours and hours learning more Swift, you will find it easier to create complex applications if you become more comfortable with the language. Swift, as mentioned before, is not something that can be described in a single hour. It is a new language that is evolving to meet the specific needs of Apple’s computing platform.
To learn more about Swift, check out Programming in Objective-C 2.0, Third Edition (Addison-Wesley Professional, 2011), Objective-C Phrasebook (Addison-Wesley Professional, 2011), Sams Teach Yourself Swift in 24 Hours (Sams, 2014), and Xcode 4 Unleashed (Sams, 2012).
Apple has also published a book (The Swift Programming Language) that covers the entirety of the Swift language, including Playground exercises. It is available directly with the iBook store on your Mac or iOS device. This isn’t just recommended reading; it’s a required download for any serious developer-to-be.