How to convert this Swift syntax into Objective C?

Question

I'm converting a swift project to objective c, but i get some trouble because i don't know how to convert follow code. Please help me. Thanks!

   public enum UPCarouselFlowLayoutSpacingMode {
    case fixed(spacing: CGFloat)
    case overlap(visibleOffset: CGFloat)
}

and

fileprivate var currentPage: Int = 0 {
    didSet {
        let character = self.items[self.currentPage]
        self.infoLabel.text = character.name.uppercased()
        self.detailLabel.text = character.movie.uppercased()
    }
}

Answer 1

The first (an enum with associated values) has no direct equivalent in Objective-C. For your particular example, you could use something like this:

typedef NS_ENUM(NSInteger, UPCarouselFlowLayoutSpacingMode) {
    UPCarouselFlowLayoutSpacingModeFixed,
    UPCarouselFlowLayoutSpacingModeOverlap
};

typedef struct {
    UPCarouselFlowLayoutSpacingMode mode;
    CGFloat amount;
} UPCarouselFlowLayoutSpacing;

You would just pass around values of type UPCarouselFlowLayoutSpacing. You could create helper functions to make these easier to create, e.g.

UPCarouselFlowLayoutSpacing UPCarouselFlowLayoutSpacingMakeFixed(CGFloat spacing) {
    UPCarouselFlowLayoutSpacing value;
    value.mode = UPCarouselFlowLayoutSpacingModeFixed;
    value.amount = spacing;
    return value;
}

UPCarouselFlowLayoutSpacing UPCarouselFlowLayoutSpacingMakeOverlap(CGFloat visibleOffset) {
    UPCarouselFlowLayoutSpacing value;
    value.mode = UPCarouselFlowLayoutSpacingModeOverlap;
    value.amount = visibleOffset;
    return value;
}

For the second, you can override the setter method of your Objective-C class's currentPage property:

- (void)setCurrentPage:(NSInteger)page {
    _page = page;

    MovieCharacter *character = self.items[page];
    self.infoLabel.text = character.name.localizedUppercaseString;
    self.detailLabel.text = character.movie.localizedUppercaseString;
}