Using a JSON array from a URL and returning rows that match a value in Swift 3

Question

I might be missing something (new to this) but I am using this Swift 3 answer on how to find an object in a NSArray.

Specifically, I want to return values from a JSON array that match a property called 'episode' (these are strings):

        let url = URL(string: "http://www.example.com/example.json")
            URLSession.shared.dataTask(with:url!, completionHandler: {(data, response, error) in
                guard let data = data, error == nil else { return }

                let json: Any?
                do{
                    json = try JSONSerialization.jsonObject(with: data, options: [])
                }
                catch{
                    return
                }

                guard let data_list = json as? NSArray else {
                    return
                }

                if let foo = data_list.first(where: {$0.episode = "Example 1A"}) {
                    // do something with foo
                    print(foo)
                } else {
                    // item could not be found
                }

            }).resume()

Even after following XCode and using AnyObject (first used Any), it says that Value of type 'Any' has no member 'episode'.

My belief is this is because I am pulling this from a URL and so it doesn't know episode is a real member. The array I am using looks like this:

[{"show": "Example", "episode": "Episode 1A", "date":"January 23"},{"show": "Example 2", "episode": "Episode 2B", "date":"December 20"}

Any ideas what the appropriate way to return rows that match the episode string I specify, like "Episode 1A"?

Note that if you move up to Swift4 you could use the Codable protocol and serialize/deserialize your custom objects much more simply. See developer.apple.com/documentation/foundation/… — Duncan C
– Duncan C, Commented Jan 24, 2018 at 1:08

rmaddy · Accepted Answer · 2018-01-23 21:16:50Z

3

json is an array of dictionary with a key of "episode".

Don't use NSArray in Swift.

Update your code as follows:

guard let data_list = json as? [[String:Any]] else {
    return
}

if let foo = data_list.first(where: {$0["episode"] as? String == "Example 1A"}) {
    // do something with foo
    print(foo)
} else {
    // item could not be found
}

Note the two changes: the cast and the way to access the "episode". Also note the use of == for equality.

answered Jan 23, 2018 at 21:16

rmaddy

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3 Comments

vadian Over a year ago

Actually the array is [[String:String]]

darkginger Over a year ago

This works for me! Thank you for the very clear answer, and I learned something.

rmaddy Over a year ago

@vadian I considered that but wasn't 100% sure. That would be a good change if it turns out to be true.

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