iOS: How can I use #define from Objective-C in Swift?

Question

I use a Constants.h file in Objective-C that contains #define and I would like to use it in Swift 3.0. Do you think it is possible?

I have different type, for example:

/*int*/        #define EVENT_ID         12
/*Class name*/ #define FORM_TO_USE      RegistrationForm_xxxx_xxx
/*String*/    #define name             @"name1"

Any ideas?

Check out this answer by me to a similar question: https://stackoverflow.com/a/46361384/433373 — Nicolas Miari, Sep 22 '17 at 09:55
In your particular case, perhaps abandon the use of `#define` constants and use actual global variables, e.g. `int EVENT_ID = 12;` in the implementation file, and `extern int EVENT_ID;` in the header, etc. — Nicolas Miari, Sep 22 '17 at 09:59
I checked but the thing is I would like to know if it is possible to use EVENT_ID in my example directly in Swift (as in objective-C) instead of writing 12. I would like to have a generic solution. — ΩlostA, Sep 22 '17 at 10:00
You can still use it as `EVENT_ID` everywhere. You just need to define it as **an actual variable** instead of a compile-time text-replacement rule :) — Nicolas Miari, Sep 22 '17 at 10:01
@Nicolas MiariI understand, but that Constants.h file contains next to 10 000 #define, and if there is a solution to create a type of "bridge" ans using it directly in Swift, it should be very cool :D — ΩlostA, Sep 22 '17 at 10:03
@Dixit Akabari But my problem is even if I put it in the Constants.h, I cannot see that in a .swift file — ΩlostA, Sep 22 '17 at 10:04
You **can** see them if you `#include` the header file in your **Bridging Header**. — Nicolas Miari, Sep 22 '17 at 10:08
@Claudio your Constants.h file add in "objective c bridging header" in build settings. — Dixit Akabari, Sep 22 '17 at 10:10

score 2 · Answer 1 · answered Sep 22 '17 at 10:38

Best Practice for Swift Constants -

Constants.swift

struct Constants {
    static let someValue = "TEST"
    static let arrayOfTests: [String] = ["foo", "bar", someValue]
}

struct Event {
    static let id = 12
    static let name = "event Name"
}
struct NotificationKey {
    static let welcome = "event Name"
}

Use:

let eventID  = Event.id
let eventName = Event.name
let aValue = Constants.someValue
let notification = NotificationKey.welcome

score 1 · Answer 2 · answered Sep 22 '17 at 10:18

1

In simple case we can use bridging header and import constant.h file and use EVENT_ID directly in code , this should work.

answered Sep 22 '17 at 10:18

user2029250

29
4

seems like it doesn't work – Zaporozhchenko Oleksandr Feb 25 '21 at 09:06

score -2 · Answer 3 · answered Sep 22 '17 at 10:16

-2

Try this instead

let EVENT_ID = 12 let FORM_TO_USE = RegistrationForm_xxxx_xxx let name = name1

answered Sep 22 '17 at 10:16

Muthu Mari

1
1
3

iOS: How can I use #define from Objective-C in Swift?

3 Answers3