Using an Objective C enum in Swift back in Objective C - objective-c

Question

I have an enum defined in Objective C and used as a datatype in a Swift object.
Now I'm using that swift object in Objective C and I'd like to access the property.
However the property isn't added to the "xxxx-Swift.h" file in the class. I know it's possible to use Swift enums in Obj C with #objc prepending it but I don't have much control over this enum since it's auto generated from existing Objective C code.

Answer 1

I'm not sure exactly what your use case is, but here is a quick example of how an enum defined in Objective-C can be used in a Swift class, which can in turn be used in Objective-C.
Here is the Objective-C header (oclib.h):
#ifndef oclib_h
#define oclib_h
#import <Foundation/Foundation.h>
typedef enum {A, B, C} oc_enum_t;
void useSwiftClassInC();
#endif /* oclib_h */
Here is the corresponding Objective-C .m file (oclib.m):
#import "oclib.h"
#import "swift_c_1-Swift.h" // Need this to have access to Swift types; the swift_c_1 part will be your product module name.
void useSwiftClassInC() {
UseEnum *ue = [[UseEnum alloc] initWithE:B i:444];
printf("In Objective-C useSwiftClassInC(): m_Enum = %d, m_Int = %d\n", ue.m_Enum, ue.m_Int);
ue.m_Enum = A;
ue.m_Int = 10;
[UseEnum printUseEnum: ue];
}
And here is the Swift file:
// Swift class that uses an enum from Objective-C
class UseEnum : NSObject // NSObject inheritance is important!
{
var m_Enum : oc_enum_t
var m_Int : Int32
init(e : oc_enum_t, i : Int32)
{
m_Enum = e
m_Int = i
}
static func printUseEnum( x : UseEnum )
{
print("In Swift UseEnum::printUserEnum: m_Enum = \(x.m_Enum), m_Int = \(x.m_Int)")
}
}
// This calls an Objective-C function that does the following:
// - creates a UseEnum object
// - prints it out from Objective-C
// - modifies it
// - calls printUseEnum(), implemented in Swift, to print the object
useSwiftClassInC()
The bridging header just has
#import "oclib.h"
You have probably seen this documentation already, but if not, here it is: https://developer.apple.com/library/ios/documentation/Swift/Conceptual/BuildingCocoaApps/MixandMatch.html
Please provide more details about your specific situation if this doesn't answer your question. Here is the output I get from the example:
In Objective-C useSwiftClassInC(): m_Enum = 1, m_Int = 444
In Swift UseEnum::printUserEnum: m_Enum = oc_enum_t(rawValue: 0), m_Int = 10
An interesting situation arises if a data type defined in Swift is used in the signature of an Objective-C function that needs to be called from Swift. Xcode won't let us import the *-Swift.h into an Objective-C header or into a bridging header. A solution is to use #class forward declaration of the Swift type. Thus, if in the above example we needed an Objective-C function that takes UseEnum as a parameter, we could have something like this in oclib.h:
...
#class UseEnum; // Forward declaration must come before UseEnum is used!
...
void useSwiftClassInC_1(UseEnum * useEnum);
...