The following is valid swift (works as expected in the XCode playground):
print("The magic happens here.")
var arr1 = Array<String?>()
arr1.append("some string")
arr1.append(nil)
print(arr1)
let arr2: Array<String?> = ["hello", nil]
print(arr2)
However fails to compile in Fire 2321:
consoleapplication227.zip (5.8 KB)