Accessing objective-c Struct from Swift

Question

I'm working on an ios application that has a mix of swift and obj-c code. One of my obj-c model classes defines a struct containing strings to assist in converting to a dictionary and back. I have the bridging header setup and I can access methods defined in my objective-c class in a swift class. What I can't figure out is how to access the static stuct to get at my property strings. Here is a snippet of my .h and .m files:

OrderItem.h

extern const struct OrderItemAttributes {
    __unsafe_unretained NSString *created;
    __unsafe_unretained NSString *created_by_id;
    __unsafe_unretained NSString *device_deleted;
} OrderItemAttributes;

@interface OrderItem : NSManagedObject {}
@property (nonatomic, strong) NSDate* created;
@end

OrderItem.m

const struct OrderItemAttributes OrderItemAttributes = {
    .created = @"created",
    .created_by_id = @"created_by_id",
    .device_deleted = @"device_deleted",
};

@implementation OrderItem
@dynamic created;
@end

I thought I would simply be able to use

OrderItem.OrderItemAttributes.created

to access the attribute strings but swift doesn't accept that syntax. Is there any way to do what I want without major changes to my objective-c code?

Answer 1

The variable OrderItemAttributes isn't part of the OrderItem namespace. It would be accessed directly as:

var foo: NSString = OrderItemAttributes.created.takeUnretainedValue()

The problem you're seeing with autocomplete occurs because OrderItemAttributes is ambiguous; it's both a type name and a variable name. Use different names for the struct type name and the global variable to avoid the ambiguity. Eg, add 'Struct' to the end of the type name:

extern const struct OrderItemAttributesStruct {
    __unsafe_unretained NSString *created;
    __unsafe_unretained NSString *created_by_id;
    __unsafe_unretained NSString *device_deleted;
} OrderItemAttributes;