Using Objective-C function in Swift which takes in a reference to a variable

Question

I have a Objective-C function which we'll call foo for the purposes of being useful to others.

something a //Define variable a as a 'something' type
[foo:&a]

How do I go about translating this into swift?

What is something? A scalar type, struct, union, class, ...? What does foo? How is the method declared? Does it modify the referenced element? – A concrete compiling example would be helpful. — Martin R
– Martin R, Commented Jun 1, 2015 at 17:42
Apologies for the vagueness. 'a' is a class in a SDK which foo, also part of the sdk, would reference to in this case return a modified class object containing error codes. — Jayden Chan
– Jayden Chan, Commented Jun 1, 2015 at 21:27

Jeef · Accepted Answer · 2015-06-01 17:51:10Z

1

In swift if you want to pass by reference you use the inout notation in your function definition

such as

func test(inout a : Double) {
    //do something
}

var d : Double = 3.5
test(&d)

If you are referring to using a function directly you would use the same &variable notation you use elsewhere

So you would just call foo(&var)

answered Jun 1, 2015 at 17:51

Jeef

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Comments

Amit89 · Accepted Answer · 2015-06-01 18:12:56Z

0

If the something is an instance of a class, it is automatically pass by reference when you do:

foo(a)

If the something is an instance of a struct, it's passed in as a copy and you shouldn't try to pass it's address around. Instead make something a class.

edited Jun 1, 2015 at 18:12

Amit89

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answered Jun 1, 2015 at 17:40

Dash

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