Swift filter nested array of objects

Question

I have an array of Business objects. Each Business object contains an array of key-value pairs, one element of which can be a nested array of ContentBlocks objects.

var masterArray = [
        Business(busName: "Dave's Cafe", busId: 1, website: "http://www.davescafe.com", latLong: (45.541, -45.609),
            actions: [["title": "About Us", "contentId": "123", "actionType": "content"],
                ["title": "Website", "url": "http://www.davescafe.com", "actionType": "web"]],
            contentBlocks:[
                ContentBlock(busName: "Dave's Cafe", busId: 1, contentId: "123", title: "Testola!", body: "Hello there!")
            ]),
        Business(busName:...
]

I can filter the array to return a specific Businesses matching a unique busId by using something like this:

let rtnArray = masterArray.filter{$0.busId == id}
    if rtnArray.count == 1{
        return rtnArray[0]
    } else {
        return // feedback that no matches were found
    }

Additionally, I'd like to return a specific contentBlock by filtering on the unique contentId (if necessary I can also pass the busId of the Business 'owner'). I'm really struggling to move forward so any pointers in the right direction would be great.

Answer 1

Here's a solution to what I think you're asking:

 var contentBlocks = masterArray
                         .flatMap{$0.contentBlocks}
                         .flatMap{$0}
                         .filter{$0.contentId == "123"}

Outputs a [ContentBlock] containing all ContentBlock objects that match the filter from within all Business objects.

1. The first flatMap makes the list of Businesses into an [ContentBlock?]
2. The flatMap flattens the [ContentBlock?] into a [ContentBlock]
3. The [ContentBlock] is filtered