Hash Define in objective C and usage in swift [duplicate] - ios

Question

I am migrating a UIViewController class to train a bit with Swift. I am successfully using Objective-C code via the bridging header but I have the need of importing a constants file that contains #define directives.
I have seen in Using Swift with Cocoa and Objective-C (Simple macros) the following:
Simple Macros
Where you typically used the #define directive to define a primitive constant in C and Objective-C, in Swift you use a global constant instead. For example, the constant definition #define FADE_ANIMATION_DURATION 0.35 can be better expressed in Swift with let FADE_ANIMATION_DURATION = 0.35. Because simple constant-like macros map directly to Swift global variables, the compiler automatically imports simple macros defined in C and Objective-C source files.
So, it seems it's possible. I have imported the file containing my constants into the bridging header, but I have no visibility from my .swift file, cannot be resolved.
What should I do to make my constants visible to Swift?
UPDATE:
It seems working with NSString constants, but not with booleans:
#define kSTRING_CONSTANT #"a_string_constant" // resolved from swift
#define kBOOL_CONSTANT YES // unresolved from swift

Answer 1

At the moment, some #defines are converted and some aren't. More specifically:
#define A 1
...becomes:
var A: CInt { get }
Or:
#define B #"b"
...becomes:
var B: String { get }
Unfortunately, YES and NO aren't recognized and converted on the fly by the Swift compiler.
I suggest you convert your #defines to actual constants, which is better than #defines anyway.
.h:
extern NSString* const kSTRING_CONSTANT;
extern const BOOL kBOOL_CONSTANT;
.m
NSString* const kSTRING_CONSTANT = #"a_string_constant";
const BOOL kBOOL_CONSTANT = YES;
And then Swift will see:
var kSTRING_CONSTANT: NSString!
var kBOOL_CONSTANT: ObjCBool
Another option would be to change your BOOL defines to
#define kBOOL_CONSTANT 1
Faster. But not as good as actual constants.

Answer 2

Just a quick clarification on a few things from above.
Swift Constant are expressed using the keywordlet
For Example:
let kStringConstant:String = "a_string_constant"
Also, only in a protocol definition can you use { get }, example:
protocol MyExampleProtocol {
var B:String { get }
}

Answer 3

In swift you can declare an enum, variable or function outside of any class or function and it will be available in all your classes (globally)(without the need to import a specific file).
import Foundation
import MapKit
let kStringConstant:String = "monitoredRegions"
class UserLocationData : NSObject {
class func getAllMonitoredRegions()->[String]{
defaults.dictionaryForKey(kStringConstant)
}

Answer 4

simple swift language don't need an macros
all #define directives.
will be let
and complex macros should convert to be func

Answer 5

The alternative for macro can be global variable . We can declare global variable outside the class and access those without using class. Please find example below
import Foundation
let BASE_URL = "www.google.com"
class test {
}