Binary search function for swift

BinarySearch.swift

import Foundation

let numbers = Array(1...1000)

func binarySearch<T: Comparable>(_ a: [T], key: T, range:Range<Int>) -> Int?{
	if range.lowerBound >= range.upperBound{ return nil}
	
	let midIndex = range.lowerBound + (range.upperBound - range.lowerBound)/2
	
	if key < a[midIndex]{
		return binarySearch(a, key: key, range: range.lowerBound..<midIndex)
	}else if key > a[midIndex]{
		return binarySearch(a, key:key, range: midIndex..<range.upperBound)
	}else{
		return midIndex
	}
}



func search(_ a: [Int], _ item: Int) -> Int{
    if a.count < 1{
        return -1
    }
    
    func binarySearch(_ a:[Int], _ low: Int, _ high: Int) -> Int{
        if low > high{
            return -1
        }
        
        let midIndex = low + (high - low)/2
        if item < a[midIndex]{
            return binarySearch(a, low, midIndex-1)
        } else if item > a[midIndex]{
            return binarySearch(a, midIndex+1, high)
        }else {
            return midIndex
        }
    }
    
    return binarySearch(a, 0, a.count-1)
}