Swift 2 Playground(Xcode 7 Beta 4) - Multiple types in an array only work when UIKit imported?

Question

I was trying out Swift arrays in the Playground, when I noticed this peculiar behaviour

The below code works fine.

import UIKit

var array = [1,2,3,"Booyaa"]

But, as soon as I remove the "import UIKit" line from the Playground, I get the following error

Playground execution failed: /var/folders/tx/tvyf1r314wj9371f491qx8wjbqbgsr/T/./lldb/11708/playground71.swift:2:17: error: 'Int' is not convertible to 'IntegerLiteralConvertible' var array = [1, 2, 3, "Booyaa"]

Why does this happen?

swift2 is pain in the arse, boy! – sriram hegde Aug 02 '15 at 14:58 — sriram hegde, Aug 02 '15 at 14:58
No, no need. It's need `import Foundation`. – Long Pham Aug 03 '15 at 03:08 — Long Pham, Aug 03 '15 at 03:08
@longpham Could you please explain in more detail? – kkaosninja Aug 03 '15 at 03:30 — kkaosninja, Aug 03 '15 at 03:30

score 1 · Accepted Answer · answered Sep 26 '15 at 05:40

The correct answer is here, in response to an identical question I posted on the Apple Dev forums => https://forums.developer.apple.com/message/35389

It's because Swift Arrays can only contain objects that are the same type. Your array has integers and a string. When you import UIKit the objects in the array become objects of type NSObject by virtue of Swift's inference engine. To see for yourself, add the line after the array definition, you'll see the type as Swift.array

import UIKit  
var array = [1,2,3,"Swift2"]  
array.dynamicType

score 0 · Answer 2 · answered Aug 03 '15 at 03:52

With high programming language this need a lexical structure for checking and compare complex type as your question. And it's implemented in Foundation framework.

Also UIKit implemented some UI api as UIView, etc... And in UIKit framework it's need using Foundation framework.

BTW: Foundation framework is core Swift, Objective-C language.

Hope this helps!

Swift 2 Playground(Xcode 7 Beta 4) - Multiple types in an array only work when UIKit imported?

2 Answers2