Binary operator '==' cannot be applied to operands of type 'Any?' and 'String' Swift iOS

问题

I have this var json : [[String : Any]] = [[:]] which contains the JSON response as follows:

{
"id": "1",
"name": "Apple",
"category_name": "Fruits"
},
{
"id": "2",
"name": "Black shirt",
"category_name": "Fashion"
},
{
"id": "3",
"name": "iPad",
"category_name": "Gadgets"
}

And I wrote an enum:

enum : Int {
        case fruits = 0, fashion, gadgets
    }

var data = [Categories: [[String: Any]]]()

Then I have this method to sort the categories:

func sortData() {
        data[.fruits] = self.json.filter({ $0["category_name"] == "Fruits" })
        data[.fashion] = self.json.filter({ $0["category_name"] == "Fashion" })
        data[.gadgets] = self.json.filter({ $0["category_name"] == "Gadgets" })
    }

After that I get an error like this

Binary operator '==' cannot be applied to operands of type 'Any?' and 'String'

Please tell me how do I solve that one?

回答1:

You should safely cast the value on the left to String, like this:

data[.fruits] = self.json.filter({ ($0["category_name"] as? String) == "Fruits" })

回答2:

The problem is that you're trying to compare values of differing types, namely Any? and String. To quickly solve the problem you might want to try and convince Swift that your Any? is actually a string value. Try replacing $0["category_name"] with ($0["category_name"] as? String), which will turn it into String?. Swift will then be able to compare the optional string with your given category string.

回答3:

Swift 5

Change following codes from

func sortData() {
        data[.fruits] = self.json.filter({ $0["category_name"] == "Fruits" })
        data[.fashion] = self.json.filter({ $0["category_name"] == "Fashion" })
        data[.gadgets] = self.json.filter({ $0["category_name"] == "Gadgets" })
    }

func sortData() {
        data[.fruits] = self.json.filter({ $0["category_name"] as? String  == "Fruits" })
        data[.fashion] = self.json.filter({ $0["category_name"] as? String == "Fashion" })
        data[.gadgets] = self.json.filter({ $0["category_name"] as? String == "Gadgets" })
    }

This will fix the error.

来源：https://stackoverflow.com/questions/47139150/binary-operator-cannot-be-applied-to-operands-of-type-any-and-string-s

标签

ios

json

swift

binary-operators