Storing different types of value in Array in Swift

Question

In Swift Programming Language, it says "An array stores multiple values of the same type in an ordered list." But I have found that you can store multiple types of values in the array. Is the description incorrect?

e.g.

var test = ["a", "b", true, "hi", 1]

Answer 1

From REPL

 xcrun swift
  1> import Foundation
  2> var test = ["a", "b", true, "hi", 1]
test: __NSArrayI = @"5 objects" {
  [0] = "a"
  [1] = "b"
  [2] =
  [3] = "hi"
  [4] = (long)1
}
  3>

you can see test is NSArray, which is kind of AnyObject[] or NSObject[]

What happening is that Foundation provides the ability to convert number and boolean into NSNumber. Compiler will perform the conversion whenever required to make code compile.

So they now have common type of NSObject and therefore inferred as NSArray

---

Your code doesn't compile in REPL without import Foundation.

 var test = ["a", "b", true, "hi", 1]
<REPL>:1:12: error: cannot convert the expression's type 'Array' to type 'ArrayLiteralConvertible'

---

 var test:Array = ["a", "b", true, "hi", 1]
<REPL>:4:18: error: cannot convert the expression's type 'Array' to type 'ExtendedGraphemeClusterLiteralConvertible'

---

but you can do this

var test : Any[] = ["a", "b", true, "hi", 1]

Because they have a common type, which is Any.

---

Note: AnyObject[] won't work without import Foundation.

var test:AnyObject[] = ["a", "b", true, "hi", 1]
<REPL>:2:24: error: type 'Bool' does not conform to protocol 'AnyObject'