How to use a swift class with a generic type in objective c

问题

I have the following swift class with a NumericType T.

@objc class MathStatistics<T: NumericType> : NSObject {
        var numbers = [T]()

        func sum() -> T? {
            if numbers.count == 0 {
                return nil
            }

            var sum = T(0)

            for value in numbers {
                sum = sum + value
            }
            return sum
        }
    }

In swift a initialize the class object as follows:

let statistics = MathStatistics<Double>()

How do I initialize the same object in Objective C? The following line does not set the numeric type T.

MathStatistics *stats = [[MathStatistics alloc] init];

回答1:

You can't. As listed in the documentation:

You’ll have access to anything within a class or protocol that’s marked with the @objc attribute as long as it’s compatible with Objective-C. This excludes Swift-only features such as those listed here:

• Generics
• Tuples
• Enumerations defined in Swift
• Structures defined in Swift
• Top-level functions defined in Swift
• Global variables defined in Swift
• Typealiases defined in Swift
• Swift-style variadics
• Nested types
• Curried functions

You'd have to get rid of generics in your class. Then you can use it in Objective-C

来源：https://stackoverflow.com/questions/31361848/how-to-use-a-swift-class-with-a-generic-type-in-objective-c