How to check if an variable of any type is an array

Question

I tried to cast a swift protocol array as any array, but failed.

protocol SomeProtocol: class{
}

class SomeClass: NSObject, SomeProtocol{
}

let protocolArray: [SomeProtocol] = [SomeClass()]
let value: Any? = protocolArray

if let _ = value as? [SomeProtocol]{
     print("type check successed")      //could enter this line
}

Above code could work as expected. However, my problem is, I have a lot of protocols, and I don't want to check them one by one. It is not friendly to add new protocol.

Is there any convenience way to do check if above "value" is a kind of array like below?

if let _ = value as? [Any]{
    print("type check successed")    //never enter here
}

edit:

Inspired by Rohit Parsana's answer, below code could work:

if let arrayType = value?.dynamicType{
    let typeStr = "\(arrayType)"
    if typeStr.contains("Array"){
         print(typeStr)
    }
}

But these code seems not safe enough, for example, you can declare a class named "abcArray".

Although we could use regular expression to check if "typeStr" matches "Array<*>", it seems too tricky.

Is there any better solution?

Swifty · Accepted Answer · 2016-09-12 07:13:07Z

1

You can use reflection:

if value != nil {
    let mirror = Mirror(reflecting: value!)
    let isArray = (mirror.displayStyle == .Collection)
    if isArray {
        print("type check succeeded")
    }
}

answered Sep 12, 2016 at 7:13

Swifty

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1 Comment

Yan Peng Over a year ago

That's awesome! Thanks!

Rohit Parsana · Accepted Answer · 2016-09-12 05:50:22Z

0

You can check the type of value using 'dynamicType', here is the sample code...

if "__NSCFArray" == "\(page.dynamicType)" || "__NSArrayM" == "\(page.dynamicType)"
    {
        print("This is array")
    }
    else
    {
        print("This is not array")
    }

answered Sep 12, 2016 at 5:50

Rohit Parsana

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1 Comment

Yan Peng Over a year ago

I am afraid it does not work. "__NSCFArray", "__NSArrayM" seems like an objc array, and I am using swift here. The dynamic type of "value" is actually "Array<SomeProtocol>"

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