Accessing global const CGFloat defined in an Objective-c .m file from Swift

问题

I have defined some constants in my .m files that I need to access form my swift code. They are defined:

const CGFloat testValue = 40.0;

and in my other objective-c .m files I can access them by using extern:

extern const CGFloat testValue

Is there an equivalent way of making these constants accessible from the .swift files?

回答1:

Add the extern to your bridging header and Swift should be able to access it.

This simple test worked for me:

ObjCTest.m

#import <Foundation/Foundation.h>

const CGFloat testValue = 40.0;

ObjCSwiftBridgeTest-Bridging-Header.h

#import <Foundation/Foundation.h>

extern const CGFloat testValue;

main.swift

println(testValue);

Output

40.0

回答2:

Just put the var declaration above the class - it will become a global variable.

来源：https://stackoverflow.com/questions/25689442/accessing-global-const-cgfloat-defined-in-an-objective-c-m-file-from-swift