+不可用：请对混合型算术使用显式类型转换或Strideable方法

Question

I'm trying to learn Swift and am looking at an old Generic example that worked in Swift 2

func increment<T: Strideable>(number: T) -> T {
    return number + 1
}

Now in Swift 4 it complains

'+' is unavailable: Please use explicit type conversions or Strideable methods for mixed-type arithmetics

Why am I getting this error and what I am doing wrong?

Answer 1

Rather than using the + operator, you can simply use Strideable.advanced(by:) .

func increment<T: Strideable>(number: T) -> T {
    return number.advanced(by: 1)
}

increment(number: 2) //returns 3
increment(number: 2.5) //returns 3.5

Answer 2

In Swift 4 use

.advanced(by: 1)

for this refer URl:- https://developer.apple.com/documentation/swift/strideable