Strange Swift Protocol

Swift protocol is very interesting yet very weird. Sometimes it behaves very strangely.

{% highlight swift %} import Foundation

protocol Command {}

struct TLDRCommand: Command {}

// Works func getOk() -> [Command] { return [TLDRCommand(), TLDRCommand(), TLDRCommand()] }

// Does not work func getFail() -> [Command] { let myArray = [TLDRCommand(), TLDRCommand(), TLDRCommand()] return myArray }

// Casting also does not work func getFail2() -> [Command] { let myArray = [TLDRCommand(), TLDRCommand(), TLDRCommand()] return myArray as [Command] }

// This works, no complain about RHS not being the type of LHS func getOk2() -> [Command] { let myArray: [Command] = [TLDRCommand(), TLDRCommand(), TLDRCommand()] return myArray }

// And this also this works func getOk3() -> [Command] { var myArray: [Command] = [] myArray.append(TLDRCommand()) myArray.append(TLDRCommand())

return myArray

} {% endhighlight %}