Swift filter for multiple dictionary keys

Question

I'm making a search bar for my app. I'm using the filter method to get the results. I want to search through multiple keys.

Array of dictionaries:

var people = [
               ["First": "John", "Last": "Doe"],
               ["First": "Steve", "Last": "Jobs"],
               ["First": "Elon", "Last": "Musk"]
             ]

I am only able to search for either "First" or "Last", but not both, with this code:

searchResults = people.filter{
            var string = $0["Last"] 
            // or "First"

            string = string?.lowercaseString

            return string!.rangeOfString(searchText.lowercaseString) != nil
        }

Answer 1

One approach would be to simply compare both fields to the search string:

var people = [
    ["First": "JohnMusk", "Last": "Doe"],
    ["First": "Steve", "Last": "Jobs"],
    ["First": "Elon", "Last": "Musk"]
]

var searchText = "Musk"

var searchResults = people.filter{
        var firstName = $0["First"]!.lowercaseString
        var lastName = $0["Last"]!.lowercaseString

       return firstName.rangeOfString(searchText.lowercaseString) != nil
              || lastName.rangeOfString(searchText.lowercaseString) != nil

}

This gives me this result:

2015-11-18 18:19:47.691 MyPlayground[36558:7031733] (
        {
        First = JohnMusk;
        Last = Doe;
    },
        {
        First = Elon;
        Last = Musk;
    }
)

Which I believe is what you want.

Answer 2

Here's an alternate approach using NSPredicate. NSPredicate has a very powerful syntax which can do some pretty nice things for you.

let firstNameQuery = "jo"
let lastNameQuery = "mus"
// [cd] means case/diacritic insensitive. %K is used to pass in key names since FIRST and LAST are reserved keywords in NSPredicate
let predicate = NSPredicate(format: "%K CONTAINS[cd] %@ OR %K CONTAINS[cd] %@", "First", firstNameQuery, "Last", lastNameQuery)
let sorted = people.filter({
    return predicate.evaluateWithObject($0)
})
// sorted would contain John Doe and Elon Musk entries

In my example I passed in different search queries for the first and last name, but you could obviously pass in the same query for both. Just demonstrates the power of this approach.