Preferences for iPhone/iPad mobile devices are set using the Desired Capabilities class. Capabilities are set for the iPhone and iPad simulators, or physical devices. The following example shows various capabilities for these iOS devices:

switch(browser) {
    case "iphone": case "ipad":
        if ( browser.equalsIgnoreCase("ipad") ) {
            caps = DesiredCapabilities.ipad();
        }

        else {
            caps = DesiredCapabilities.iphone();
        }

        caps.setCapability("appName",
                           "https://myapp.com/myApp.zip");
        
        caps.setCapability("udid", 
                           "12345678"); // physical device
        caps.setCapability("device",
                           "iPhone"); // or iPad

        mobileDriver.set(new IOSDriver<MobileElement>
                         (new URL("http://127.0.0.1:4723/wd/hub"),
                         caps));

        break;