Add to Asset Catalog with icon files generated by Photoshop App Icon Template in https://developer.apple.com/design/resources/

Contents.json

{
  "images" : [
    {
      "size" : "20x20",
      "idiom" : "iphone",
      "filename" : "Icon-App-20x20@2x.png",
      "scale" : "2x"
    },
    {
      "size" : "20x20",
      "idiom" : "iphone",
      "filename" : "Icon-App-20x20@3x.png",
      "scale" : "3x"
    },
    {
      "size" : "29x29",
      "idiom" : "iphone",
      "filename" : "Icon-App-29x29@1x.png",
      "scale" : "1x"
    },
    {
      "size" : "29x29",
      "idiom" : "iphone",
      "filename" : "Icon-App-29x29@2x.png",
      "scale" : "2x"
    },
    {
      "size" : "29x29",
      "idiom" : "iphone",
      "filename" : "Icon-App-29x29@3x.png",
      "scale" : "3x"
    },
    {
      "size" : "40x40",
      "idiom" : "iphone",
      "filename" : "Icon-App-40x40@2x.png",
      "scale" : "2x"
    },
    {
      "size" : "40x40",
      "idiom" : "iphone",
      "filename" : "Icon-App-40x40@3x.png",
      "scale" : "3x"
    },
    {
      "size" : "60x60",
      "idiom" : "iphone",
      "filename" : "Icon-App-60x60@2x.png",
      "scale" : "2x"
    },
    {
      "size" : "60x60",
      "idiom" : "iphone",
      "filename" : "Icon-App-60x60@3x.png",
      "scale" : "3x"
    },
    {
      "size" : "20x20",
      "idiom" : "ipad",
      "filename" : "Icon-App-20x20@1x.png",
      "scale" : "1x"
    },
    {
      "size" : "20x20",
      "idiom" : "ipad",
      "filename" : "Icon-App-20x20@2x.png",
      "scale" : "2x"
    },
    {
      "size" : "29x29",
      "idiom" : "ipad",
      "filename" : "Icon-App-29x29@1x.png",
      "scale" : "1x"
    },
    {
      "size" : "29x29",
      "idiom" : "ipad",
      "filename" : "Icon-App-29x29@2x.png",
      "scale" : "2x"
    },
    {
      "size" : "40x40",
      "idiom" : "ipad",
      "filename" : "Icon-App-40x40@1x.png",
      "scale" : "1x"
    },
    {
      "size" : "40x40",
      "idiom" : "ipad",
      "filename" : "Icon-App-40x40@2x.png",
      "scale" : "2x"
    },
    {
      "size" : "76x76",
      "idiom" : "ipad",
      "filename" : "Icon-App-76x76@1x.png",
      "scale" : "1x"
    },
    {
      "size" : "76x76",
      "idiom" : "ipad",
      "filename" : "Icon-App-76x76@2x.png",
      "scale" : "2x"
    },
    {
      "size" : "83.5x83.5",
      "idiom" : "ipad",
      "filename" : "Icon-App-83.5x83.5@2x.png",
      "scale" : "2x"
    },
    {
      "size" : "1024x1024",
      "idiom" : "ios-marketing",
      "filename" : "Icon-App-1024x1024.png",
      "scale" : "1x"
    }
  ],
  "info" : {
    "version" : 1,
    "author" : "xcode"
  }
}

THANKS!