Swift filter an array inside a struct by another array

Question

I've got an array of Profile's (defined from a custom struct), and inside this, I have a [String] of interests.

I want to filter out any profiles which don't match an array of preferences, but can't seem to get my filtering to work.

The error I get is

"Cannot convert value of type '[String]' to expected argument type 'String'.

What am I missing?

Once complete, I'd expect userProfiles to contain only John and Harry.

struct Profile {
    var name: String
    var interests: [String]
}


var userProfiles: [Profile] = [
    Profile(name: "John", interests: ["Basketball", "Football", "Rowing"]),
    Profile(name: "Andrew", interests: ["Cycling", "Swimming", "Boxing"]),
    Profile(name: "Harry", interests: ["Hockey", "Baseball"])
]


let preferenceInterests = ["Basketball", "Hockey"]


userProfiles = userProfiles.filter({ (userProfile) -> Bool in
    print("\(userProfile.name): \(userProfile.interests)")
    return preferenceInterests.contains(userProfile.interests) //error here
})

Answer 1

The problem is that userProfile.interests is an array itself. Based on your example and expected output of John and Harry, it seems what you are actually trying to achieve is to keep the users who have at least 1 matching interest compared to your preferenceInterests input.

To achieve that, you need to change the body of your filter and use contains(where:) instead of contains to check if there is a match in interests.

let filteredUsers = userProfiles.filter { userProfile in
    preferenceInterests.contains(where: { interest in userProfile.interests.contains(interest) })
}