Often regulation will stop online casinos from putting their apps in the Apple App store, and with no third party apps available on iPhones, you probably will have to just play in your mobile browser. If there is regulation, or no regulation stopping online casinos, in your country it's likely you can download iOS apps. Android users are a in a different situation, with these devices allowing third party downloads, which means that you can download gambling apps directly from the company that offers it. Always do your homework before downloading a gambling app to an Android device, because there is far less restrictions placed on their operations.