Alternate Icon in iOS 10.3

Question

I have the info on how to set up alternate icons in iOS 10.3 adding the key in the Info.plist. However, what I am not sure of is which sizes are needed for each alternate.

Answer 1

Since the biggest problem is how to configure the icon image source and info.plist, here is a sample to tell you how to set alternate icons in iOS 10.3, implemented in Swift 3.

1. If your app doesn't support iPad, the icon image source can be 60pt@2x and 60pt@3x (120x120 180x180), and the 20pt 29pt and 40pt all can be generated from the 60pt image. So, your alternate icon image source should also be 60pt@2x and 60pt@3x, if it is a iPhone-only app. And it should be 83.5pt, if your app supports iPad Pro.

2. Like what you saw in the picture, the alternate icon image should be added to the project as a png file (the blackBgColor image in my sample), but not added to Assets.xcassets.

3. The configuration for alternate icons in info.plist is kinda complicated, so if this is your first time doing this, I suggest you copy my code in plist. And, notice my alternate icon's name (blackBgColor) has beed used TWICE in plist, if you are gonna change the icon's name based on my version, make sure you changed the name in both of the two places.

   CFBundleIcons
   
       CFBundleAlternateIcons
       
           blackBgColor
           
               CFBundleIconFiles
               
                   blackBgColor
               
               UIPrerenderedIcon
               
           
       
       CFBundlePrimaryIcon
       
           CFBundleIconFiles
           
               AppIcon60x60
           
       
   
   

Now, code in ViewController will be simple.

import UIKit

class ViewController: UIViewController {

    override func viewDidLoad() {
        super.viewDidLoad()
    }

    @IBAction func changeAppIcon(_ sender: Any) {

        if UIApplication.shared.supportsAlternateIcons {
            print("you can change this app's icon")
        }else {
            print("you cannot change this app's icon")
            return
        }

        if let name = UIApplication.shared.alternateIconName {
            // CHANGE TO PRIMARY ICON
            UIApplication.shared.setAlternateIconName(nil) { (err:Error?) in
                print("set icon error：\(String(describing: err))")
            }
            print("the alternate icon's name is \(name)")
        }else {
            // CHANGE TO ALTERNATE ICON
            UIApplication.shared.setAlternateIconName("blackBgColor") { (err:Error?) in
                print("set icon error：\(String(describing: err))")
            }
        }
    }

}