Why dont you download the XCode? It's available for free from https://developer.apple.com/xcode/
You have an iOS Simulator that comes bundled with XCode with which you can simulate apps and webpages across iOS Devices.
That said, CS6 is supposed to have revamped PhoneGap support with a new emulator that can test layouts of the apps/ HTML you build in DW. More on that here: http://www.adobe.com/in/products/dreamweaver/features.html#categorylens_aa0_featureset_27c b
You could also get the latest version of PhoneGap directly here: http://phonegap.com/start#ios-x4