Well, there is THE software to make IOS/OSX apps. Xcode. It is free, although very large so you are going to need a fairly decent connection to get it.
However, be advised that Xcode and Objective-c are not something that you are going to be able to sit down with for a few hours and then begin to use to whomp up really impressive apps. The learning curve is very long and steep. By the way, Xcode is the programming suite and Obj-c is the language.
I don't mean to discourage you by any means. I encourage anyone who is interested in learning programming to give it a try. But just realize that you are not going to write the next Angry Birds in your first month. Have fun learning how to make a button and click on it to do something, then move on to the next level.
First, get a beginning Objective-C book. The language doesn't change at all - at least at the beginner level. You will have to know some basic Obj-c before you do anything with Xcode besides make pretty windows.
My experience says don't waste your money buying an expensive XCode book. The suite changes too much and too often and leaves the book behind. Get your Xcode info from the web.
Go for it.