Icon image comes from: https://openclipart.org/detail/22309/apple-icon and is public domain.
Icon resources were generated using: http://romannurik.github.io/AndroidAssetStudio/icons-launcher.html with settings: http://romannurik.github.io/AndroidAssetStudio/icons-launcher.html#foreground.type=image&foreground.space.trim=1&foreground.space.pad=0&foreColor=607d8b%2C0&crop=0&backgroundShape=none&backColor=ffffff%2C100&effects=none which produces art under CC 3.0: http://creativecommons.org/licenses/by/3.0/