斯威夫特：返回数字 < 10

Question

That's the code:

import Foundation

func hasAnyMatches(list: [Int], condition: Int -> Bool) -> Bool {
    for item in list {
        if condition(item) {
            return true
        }
    }
    return false
}

func lessThanTen(number: Int) -> Bool {
    return number < 10
}

var numbers = [20, 19, 7, 12]
hasAnyMatches(numbers, condition: lessThanTen)

There is a return true within the if condition and a return false at the end of func hasAnyMatches() . Why is the return false needed?

Answer 1

Without explicitly "telling it" to return something, no function returns false "automatically". I am not writing in swift but I am sure if you take away the return false it'll throw a warning.

The lessThanTen simply returns a bool if the number is smaller than 10.

number < 10 is a statement checking if something is true or false . Hence the return type bool of lessThanTen

Answer 2

You can do like, for such condition.

let LESS_THAN_TEN = 1
let LESS_THAN_HUNDRED = 2

func hasAnyMatch (list: [Int], condition: Int)-> Bool{
 var x = false;
 switch  condition {
 case LESS_THAN_TEN :
    for a in list {
        if a < 10 {
            x = true
                break
            }
        }
 break

 case LESS_THAN_HUNDRED :
    for a in list {
        if a < 100 {
            x = true
            break
        }
    }

 break

 default:
    x = false
}
   return x
}

var isLessThanTen = hasAnyMatch([14, 45, 12, 65], condition: LESS_THAN_TEN)
print(isLessThanTen)