I'm working on iOS app and part of what I'm making is an advanced search interface. The default iOS search components allow for text entry and for a "scope bar". That is, a bar which allows you to choose which property (or properties) of your "target object" you want to match. If we were designing a books search app, here's what might look like:
This works well, however there are two limitations here.
The user has no preset search terms to choose from. While this is not bad, I'm looking for something a little different. I want to show the user a list of all existing authors and let them choose from the list.
Only one property can be searched against at a time, unless you explicitly provide an "all" button. But even, then, it's all or nothing. What if I want to search Title and Author, but not Content?
How would you design such a search control? Instead o a scope bar, I was thinking along the lines of a scope "chart" where the user taps a button and is shown a list of options. In the list, they can choose from an option, or, optionally, a custom keyword.
Is this a bad idea for user experience? How would you create this visually, to match iOS conventions?