Open Radar

 
Summary:
In swift, when defining an inout parameter to a function, the purpose is to directly access and modify that original variable. However, if the assignment isn't instant, in a case were you're waiting for a network request or such, the original variable will be left with it's original value.

Run the attached example project and read the line comments. I have provided two different scenarios, the first were the inout parameter works as expected, and the other were it doesn't.

Pseudo code explaining the problem:

var string: String?

func randomize(inout randomizedString: String?) {
    randomizedString = "4" // guaranteed to be random

    print(self.string) // prints 4
}

func asyncRandomize(inout randomizedString: String?) {
    dispatch_after(seconds: 2) {
        randomizedString = "4" // guaranteed to be random

        print(self.string) // prints nil
    }
}

randomize(&string)

string = nil // resetting it
asyncRandomize(&string)

Steps to Reproduce:
Run the attached project and see the comments and prints

Expected Results:
Both scenarios will set the &string, even after a async call

Actual Results:
The first scenario sets the variable, the second leaves it untouched

Version:
Xcode 6.1.1 6A2006

Notes:
A workaround is to use a closure instead, but that's not what I was looking for.