什么是Objective-C相当于一个空的Swift OptionSet？

Question

Please take a look at this simple Swift code:

UIView.animate(withDuration: duration, delay: interButtonDelay * Double(expanding ? index : index + 1), options: [], animations: {
            button.transform = expanding ? .init(scaleX: self.scale, y: self.scale) : .identity
            button.alpha = expanding ? 0.0 : 1.0
        }, completion: nil)

Here an empty array is passed into the options parameter. I would like to find out what is the correct Objective-C equivalent to doing this. I assume it should be passing 0, but I want to be completely sure. Unfortunately the docs not telling anything regarding this.

Answer 1

Swift's OptionSet was created to make bitmasks more pleasant to use. In Swift, you spell the combined value as if it were a collection; in Objective-C, it's an integral value, built with bitwise operators:

NSUInteger options = UIViewAnimationOptionLayoutSubviews | UIViewAnimationOptionRepeat | UIViewAnimationOptionCurveEaseOut;

The Objective-C equivalent to an empty OptionSet is therefore indeed just 0.