You can login to Salesforce via your iPhone, iPad or Android device by downloading the Salesforce app from the app store and using your production or sandbox login.
You can also login from a mobile device through a browser which will give you the same view that you see from the desktop login.
Login via the mobile app:
Download the Salesforce app from the App Store.
Open the app on your device and select the environment that you want to login to. Use the sandbox option for testing.
Enter your login credentials and click Log In to Sandbox.