sorting array of objects swift 4

Question

I have an array of object, each object contains a discount rate , I need to sort them increasingly by their rate,

struct ShopDetails {
    var shopId: Int?
    var discountRate: String?
    init(with json: Dictionary<String,Any>) {
        shopId = json["id"] as? Int
        discountRate = json["discount"] as? String

    }

I tired to sort them using this method;

 func getShopsByDiscount() {
        let sortedImages = self.copyOfShops.sorted(by: { (shop1: ShopDetails, shop2: ShopDetails) -> Bool in
            return Int(shop1.discountRate) < Int(shop2.discountRate)
        })

    }

I tried to cast the rate to integer, since its been received form the backend as string, but I got an error: value of type Any has no member discountRate. any idea how to do it? if there is a way to do it without casting it will be better

Answer 1

First, you need to verify that the array you're starting with is of type [ShopDetails] . The error indicates that this is probably an Objective-C NSArray , which won't work as well in Swift. If you're unclear about this, I suggest you Google the topic: there's no reason to use NSArray in Swift.

Below, I assume the array is the correct type ( [ShopDetails] ). From here, you need to do two additional things, because discountRate is of type String? .

1. You need to check if the string is actually there
2. You need to check if it can actually be expressed as an Int .

With these things in mind, your sort function can look like this:

let sortedImages = copyOfShops.sorted(by: {
    (shop1: ShopDetails, shop2: ShopDetails) -> Bool in
    if let shop1String = shop1.discountRate, let shop1Value = Int(shop1String),
        let shop2String = shop2.discountRate, let shop2Value = Int(shop2String) {
        return shop1Value < shop2Value
    }
    return true
})

That being said, the best way to handle this is to change the type of discountRate from String? to Int , and do the above checks when you init(with json: Dictionary<String,Any>) . If the server giving you the dictionary is something you control, have it switch to passing back Ints instead of Strings, and stop dealing with optionals if you don't have to.