Welcome to the Treehouse Community

Want to collaborate on code errors? Have bugs you need feedback on? Looking for an extra set of eyes on your latest project? Get support with fellow developers, designers, and programmers of all backgrounds and skill levels here with the Treehouse Community! While you're at it, check out some resources Treehouse students have shared here.

Looking to learn something new?

Treehouse offers a seven day free trial for new students. Get access to thousands of hours of content and join thousands of Treehouse students and alumni in the community today.

Start your free trial

iOS Functions in Swift Adding Power to Functions Returning Complex Values

Posted by 陳 聖捷
陳 聖捷
2,651 Points

My result always present the infinite decimal. How to make it to four decimal places?

my code is:

func coordinates(for location:String)->(Double,Double){ var lat = 0.0 var lon = 0.0 switch location { case "Eiffel Tower": lat = 48.8582 ;lon = 22.2945 case "Great Pyramid": lat = 29.9792;lon = 31.1344 case "Sydey Opera House": lat = 33.8587;lon = 151.2140 default: lat = 0;lon = 0 } return (lat,lon) }

after that I got the result is infinite decimal

functions.swift 
// Enter your code below
func coordinates(for location:String)->(Double,Double){
    var lat = 0.0
    var lon = 0.0
    switch location {
    case "Eiffel Tower": lat = 48.8582 ;lon = 22.2945
    case "Great Pyramid": lat = 29.9792;lon = 31.1344
    case "Sydey Opera House": lat = 33.8587;lon = 151.2140
    default: lat = 0;lon = 0
    }
    return (lat,lon)
}

1 Answer

David Papandrew
David Papandrew
8,386 Points
David Papandrew
David Papandrew
8,386 Points

There are several ways to deal with repeating decimals and number formatting.

One quick solution is to use the "round" function (you'll need to import Foundation or UIKit to use this).

So for instance:

import Foundation

// Enter your code below
func coordinates(for location:String)->(Double,Double){
    var lat = 0.0
    var lon = 0.0
    switch location {
    case "Eiffel Tower": lat = 48.8582 ;lon = 22.2945
    case "Great Pyramid": lat = 29.9792;lon = 31.1344
    case "Sydey Opera House": lat = 33.8587;lon = 151.2140
    default: lat = 0;lon = 0
    }
    return (lat,lon)
}

let result = coordinates(for: "Eiffel Tower")
round(result.0) //rounds to nearest whole number, no decimal (e.g. displays "49")
round(result.0*100)/100 //rounds to 2 decimal places (displays 48.86)
round(result.0*1000)/1000 //rounds to 3 decimal places, etc. (displays 48.858)

Another solution is to use the NumberFormatter class. You can read more about it here:

https://developer.apple.com/reference/foundation/numberformatter

Good luck.