When would you choose an emulator or simulator, and when must you use a real device?

I think of it as a question: does this test depend on real hardware or real-world conditions?

I choose an emulator or simulator when:

• A new feature has just landed and I want quick feedback on the flow.
• I need to check layouts on many screen sizes or OS versions quickly.
• I want to reproduce a bug on a specific OS version I don’t have in the office.
• I need easy tools: screenshots, setting a fake GPS location, changing language, slow network profiles.

I use a real device when testing:

• Camera, NFC, Bluetooth, sensors, biometrics (Face ID, fingerprint).
• Push notifications and interruptions like real phone calls.
• Performance, battery, heat and memory on low-end devices.
• Real networks: switching Wi-Fi to 4G, weak signal in an elevator.
• Manufacturer quirks, like Samsung keyboards or aggressive battery savers.
• Touch feel and gestures, and the final release sign-off.

Example: I verify a new settings screen on three emulator sizes in ten minutes, then confirm the QR scanner and payment flow on a real iPhone and a low-end Samsung.

Learn more: Simulators and Emulators