How to declare a constant in swift that can be used in objective c

Question

if I declare the swift constant as a global constant like:

let a = "123" 

but the a cannot be found in objective c.

How to solve this?

Answer 1

From Apple Doc:

You’ll have access to anything within a class or protocol that’s marked with the @objc attribute as long as it’s compatible with Objective-C. This excludes Swift-only features such as those listed here:

1. Generics
2. Tuples
3. Enumerations defined in Swift
4. Structures defined in Swift
5. Top-level functions defined in Swift
6. Global variables defined in Swift
7. Typealiases defined in Swift
8. Swift-style variadics
9. Nested types
10. Curried functions

Therefore its not possible to access global variables(Constants) or global functions defined in Swift.

Possible Solutions:

1. From the Apple Document Swift programming language, You can Declare Type Properties as

   class var constant: Int =  {     return 10 }() 

   But currently in Swift(beta-3) Type properties are not supported.

2. You can declare a Class function to get a constant value:

   In Swift:

   class func myConst() -> String {      return "Your constant" } 

Accessing from Objective-C:

 NSString *constantValue = [ClassName myConst];  NSLog(@"%@", constantValue);