根据过滤器数组过滤UICollectionView

Question

I am having a problem that I can't find a good answer to by myself.

I have an array containing objects that contain information about companies. Based on this objects I create a collection view where I populate the items from the information inside those objects.

var suppliers = [Suppliers]()

Now I want to add buttons with specific filters. When pressed on one or more of those buttons the collection view should update with the filters applied.

Therefore I made a few buttons and when pressed I add them to an array containing all the filters.

var filters = [Category]()

After that I call a method that should do the filtering and update the collection view.

private func filter()
{
    if filters.count > 0 {
        suppliers.filter({ ($0.category!).contains(filters)})
    }
}

Unfortunately I can't comparison like that, according to xCode. How do I achieve this filtering correctly?

edit: See the structure of the object below.

struct Supplier : JSONJoy {

    var about: String?
    var category: Array<Category>?
    var logo: String?
    var name: String?

    init(_ decoder: JSONDecoder) {
        name = decoder["name"].string
        logo = decoder["logo"].string
        about = decoder["about"].string
        if let ctgrys = decoder["category"].array {
            category = Array<Category>()
            for ctgryDecoder in ctgrys {
                category?.append(Category(ctgryDecoder))
            }
        }
}

struct Category : JSONJoy {
    var id: Int?
    var name: String?

    init(_ decoder: JSONDecoder) {
        id = decoder["id"].integer
        name = decoder["name"].string
    }

}

Answer 1

1) $0.category! is [Category] type. And you have [Category].contains call which requires (Category) throws -> Bool parameter, but in your case it is filters variable with [Category] type

2) You never apply your filter result

This is possible implementation of your filtering, if I understand your needs correctly:

private func filter() -> [Supplier] {
    if filters.count > 0 {
        return suppliers.filter { supplier in
            return supplier.category?.contains { supplierCategory in
                return filters.contains {
                    return supplierCategory.id == $0.id
                }
            } ?? false
        }
    } else {
        return suppliers
    }
}

Answer 2

We need to fix a couple of details that are going to make our lifes easier :)

1. Category becomes Equatable and Hashable

struct Category: JSONJoy, Equatable, Hashable {
    var id: Int?
    var name: String?

    init(_ decoder: JSONDecoder) {
        id = decoder["id"].integer
        name = decoder["name"].string
    }
    var hashValue: Int { get { return id?.hashValue ?? 0 } }
}

func ==(left:Category, right:Category) -> Bool {
    return left.id == right.id && left.name == right.name
}

2. Supplier does not like an optional category property

struct Supplier: JSONJoy {

    var about: String?
    var category = [Category]() // <- I changed this
    var logo: String?
    var name: String?

    init(_ decoder: JSONDecoder) {
        name = decoder["name"].string
        logo = decoder["logo"].string
        about = decoder["about"].string
        if let ctgrys = decoder["category"].array {
            category = Array<Category>()
            for ctgryDecoder in ctgrys {
                category.append(Category(ctgryDecoder))
            }
        }
    }
}

3. Now let't filter them all

You have your list of suppliers and your list of filters

var suppliers = [Supplier]()
var filters = [Category]()

Now I am not sure about how you want to filter suppliers .

However IF you want all the suppliers having at least a filter listed in filters then

let requiredFilters = Set(filters)
let supplierWithAtLeastOneRequiredFilter = suppliers.filter { !Set($0.category).intersect(requiredFilters).isEmpty }

On the other hand IF you want all the suppliers having all the filters listed in filters then

let requiredFilters = Set(filters)
let supplierWithEveryRequiredFilter = suppliers.filter { Set($0.category).isSupersetOf(filters) }

Answer 3

Assuming filtered is the filtered array of Supplier . and AllData is the full array of Supplier . And you want to filter only items which contain the word "ao" at their name property.

  filtered  = AllData.filter {
                $0.name.rangeOfString("ao", options: .CaseInsensitiveSearch) != nil
            }
        if(filtered.count == 0){
           //No Results - 
        } else {
              //There are results - update the tableView data source accordingly
        }