How to use sin(_ : ) with a FloatingPoint value in Swift 3 [duplicate]

问题

This question already has answers here:

Making Swift generics play with overloaded functions (2 answers)

Closed last year.

 import Foundation
 public func sine <T: FloatingPoint   > (_ x: T  ) -> T{
    return sin(x)
 }
 // Error: Cannot invoke 'sin' with an argument list of type '(T)'

Is there a way around this? Many thanks.

回答1:

You can make a sin method that accepts FloatingPoint type also as follow:

import UIKit

func sin<T: FloatingPoint>(_ x: T) -> T {
    switch x {
    case let x as Double:
        return sin(x) as? T ?? 0
    case let x as CGFloat:
        return sin(x) as? T ?? 0
    case let x as Float:
        return sin(x) as? T ?? 0
    default:
        return 0 as T
    }
}

Another option is adding a method or a computed property extension to FloatingPoint type as follow:

extension FloatingPoint {
    var sin: Self {
        switch self {
        case let x as Double:
            return UIKit.sin(x) as? Self ?? 0
        case let x as CGFloat:
            return UIKit.sin(x) as? Self ?? 0
        case let x as Float:
            return UIKit.sin(x) as? Self ?? 0
        default:
            return 0 as Self
        }
    }
}

来源：https://stackoverflow.com/questions/39283419/how-to-use-sin-with-a-floatingpoint-value-in-swift-3