Great idea for a PR! Unfortunately this breaks Obj-c compatibility (run the tests), as there are few Swift features here that are not compatible with obj-c.

A few suggestions:

1. Default arguments don't work in obj-c. you must declare the simpler method and then call into the more complex method with the default.

2. Since you have made public the the string extensions for isValidWebsite() and isValidEmail(), I suggest changing them to computed properties (vars instead of funcs) as this are more consistent with swift 3's isEmpty which is now a var. Or else make them private and put them in an internal utility.

3. the filter argument is an array of a swift enum. This cannot be represented in obj-c. I would suggest using an option set here. Swift option set types are not bridgeable to obj-c but you can go the other way around. see http://stackoverflow.com/questions/32530018/accessing-swift-optionsettype-in-objective-c.

Also, remember that an option set means you can have ANY of the passed in filters apply. So you can't have if, else if etc logic as you do in the block other function as it will mean only ONE of the filters will apply.

Could you also write some new tests for the added functionality but also keep the original tests as they were to ensure correct regression testing.