Development Environment

OS X El Captain 10.11.2
Xcode Version 8.0

#Language
Swift 3.0

#Step
1 Create Int Extension file

Int+Extension.swift

import UIKit

extension Int {
    // 数値省略処理
    func AbbreviationFormatter () -> String {
        let numberFormatter = NumberFormatter()
        typealias Abbreviation = (threshold:Double, divisor:Double, suffix:String)
        // 単位のパターン宣言はここで. Add more abbreviation from here
        let abbreviationsUnits:[Abbreviation] = [(0, 1, ""),(100.0, 1000.0, "K"),(100_000.0, 1_000_000.0, "M"), (100_000_000.0, 1_000_000_000.0, "B")]
 
        let initialValue = Double (abs(self))
        let abbreviation:Abbreviation = {
            var after = abbreviationsUnits[0]
            for temp in abbreviationsUnits {
                if (initialValue < temp.threshold) {
                    break
                }
                after = temp
            }
            return after
        } ()
        let actualValue = Double(self) / abbreviation.divisor
        numberFormatter.positiveSuffix = abbreviation.suffix
        numberFormatter.negativeSuffix = abbreviation.suffix
        numberFormatter.allowsFloats = true
        numberFormatter.minimumIntegerDigits = 1
        numberFormatter.minimumFractionDigits = 0
        numberFormatter.maximumFractionDigits = 1
        return numberFormatter.string(from: NSNumber (value:actualValue))!
    }
}

2 You can use that extension with int parameter

ViewController.swift

import UIKit

class ViewController: UIViewController {

    override func viewDidLoad() {
        super.viewDidLoad()
        
        let number1 = 5000
        let number2 = 500000
        let number3 = 5000000
        let number4 = 5000000000
        
        print (number1.AbbreviationFormatter())
        print (number2.AbbreviationFormatter())
        print (number3.AbbreviationFormatter())
        print (number4.AbbreviationFormatter())

        // Do any additional setup after loading the view, typically from a nib.
    }

    override func didReceiveMemoryWarning() {
        super.didReceiveMemoryWarning()
        // Dispose of any resources that can be recreated.
    }
}

3 Output will be following:
5K 0.5M 5M 5B

4 Done