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iOS

Posted by John Sanchez
John Sanchez
3,325 Points

Optionals question swift

Why is this not an error

var x: String x = "Hello World" Shouldn't an error be thrown since the type of x is String and before x is assigned to "Hello World" it is equal to nil (not a string)?

I thought that you had to do something like this: var x: String? x = "Hello World"

Thanks.

1 Answer

miguelcastro2
PLUS
miguelcastro2
Courses Plus Student 6,573 Points
miguelcastro2
miguelcastro2
Courses Plus Student 6,573 Points

When you declare x:

var x: String

The variable x is uninitialized, but it is not equal to nil since the variable has not been declared as an optional by using the ? directive. When you set x equal to "Hello World", it then initializes a String to that variable. However, you could not use a statement like this:

if x == nil {
   println("X is not set")
}

Unless you set the variable as an optional:

var x: String?

In your code you are basically saying that the variable x can only ever have the value of a String