Creating a game for iPhone or iPad is easy with Construct 2. If you haven't already, download the Free edition and get going with the Beginner's guide!
Note the term iOS is the operating system that both iPhone and iPad run. iOS is used to refer to either the iPhone or the iPad.
You'll need to add touch controls. See this tutorial on touch controls for help on that.
Different devices have different size screens. See supporting multiple screen sizes.
Testing and publishing
You can preview over Wifi during development for rapid testing. (This requires a Construct 2 license.)
For best results, publish iOS apps using Cordova and target iOS 8.0+.
Another option is simply to publish your app to the web. iOS allows web pages to act like native apps. These are called web apps, and have various advantages and disadvantages compared to publishing in the App Store. See the tutorial Making an iOS web app for more.
To publish native apps, you have to be a registered iOS developer with Apple which costs $99/year. See How to become an iOS developer. You don't have to be a registered iOS developer to publish a web app.
You'll need a Construct 2 license to publish to iOS. See the store for options.
How to make Android games
How to make a Windows 8 app
How to make a Windows Phone 8 app
How to export for Firefox Marketplace
Publishing and promoting your Construct 2 game
Happy app making!