Swift check if value is of type array (of any type)

问题

How can I check in Swift if a value is an Array. The problem is that an array of type Int can apparently not be casted to an array of type Any. Suppose I have an array myArray of type Int and execute the following:

if let array = myArray as? [Any] { return true }

it doesn't return true (which surprises me actually). The same thing appears with dictionaries. I want a dictionary of type String, Any (meaning that Any can be any type). How can I check if it is?

Thanks in advance.

回答1:

Got it working like this, although it's not as beautiful as I would've hoped:

protocol ArrayType {}
extension Array : ArrayType {}

let intArray : Any = [1, 2, 3]
let stringArray : Any = ["hi", "hello", "world"]

intArray is ArrayType       // true
stringArray is ArrayType    // true

EDIT: I think I misunderstood your question before, now I got it though:

let intArray = [1, 2, 3]

let anyArray = intArray.map{ $0 as Any }

This is the only way to my knowledge.

回答2:

Got it now, with the idea of @Kametrixom. It's extraordinary ugly but at least it works.

private protocol CJSONArrayType {
    func toAny() -> [Any]
}
extension Array: CJSONArrayType {
    private func toAny() -> [Any] {
        return self.map { $0 as Any }
    }
}
extension NSMutableArray: CJSONArrayType { }
extension NSArray: CJSONArrayType {
    private func toAny() -> [Any] {
        var result = [Any]()
        for item in self {
            result.append(item as Any)
        }
        return result
    }
}

private protocol CJSONDictionaryType {
    func toStringAny() -> [String: Any]
}
extension Dictionary: CJSONDictionaryType {
    private func toStringAny() -> [String : Any] {
        var result = [String: Any]()
        for item in self {
            result[item.0 as! String] = item.1 as Any
        }
        return result
    }
}
extension NSMutableDictionary: CJSONDictionaryType { }
extension NSDictionary: CJSONDictionaryType {
    private func toStringAny() -> [String : Any] {
        var result = [String: Any]()
        for item in self {
            result[item.0 as! String] = item.1 as Any
        }
        return result
    }
}

回答3:

If you want to parse JSON, there are only a few supported types which are at least AnyObject rather than Any.

Then it's very easy to check for Array

func checkArray(item : AnyObject) -> Bool {
  return item is Array<AnyObject>
}

let integer = 1
let string = "one"
let array = ["one", "two", "three"]
let dictionary = ["one" : 1, "two" : 2]

checkArray(integer) // false
checkArray(string) // false
checkArray(array) // true
checkArray(dictionary) // false

Apple highly recommends to constrain the types at compile time as much as possible

来源：https://stackoverflow.com/questions/32033993/swift-check-if-value-is-of-type-array-of-any-type