The cell phone doesn't have a lamp or projector lens: the screen alone doesn't project any image onto the wall, and apps that promise this only simulate the effect. What works is sending the cell phone screen to a projector, either wired or wirelessly. There are four ways, and each requires different equipment.
What you need to project your phone screen.
1. Projector with wireless mirroring
Many projectors, including portable ones, already come with Wi-Fi and support screen mirroring. On Android, the shortcut is in the quick settings panel, named "Cast" or "Smart View" on Samsung devices. On iPhone, it's called "Screen Mirroring," which works with projectors compatible with AirPlay. With Chromecast built-in or AirPlay, the phone and projector are on the same Wi-Fi network; Miracast connects directly, without a router. The projector's manual indicates which of these standards it supports.
2. Chromecast connected to the projector
Projectors with only an HDMI input gain wireless streaming with a Chromecast or other Google Cast-compatible device. (In the app) Google Home, Tap on the device and then on “Cast my screen”. Video apps like YouTube have their own cast button, which sends only the video and leaves the phone free for other things.
3. USB-C to HDMI cable
This is the most stable method, without image lag. Several Android devices with USB-C have video output, such as the latest Galaxy S models: all you need is a USB-C to HDMI adapter and a cable to the projector. From the iPhone 15 onwards, the USB-C port also sends video; on iPhones with Lightning, the component is Apple's Lightning to Digital AV Adapter. Not all phones with USB-C have video output, so look for "DisplayPort Alt Mode" in your model's specifications before buying the adapter.
4. Smart TV instead of projector
If the goal is simply to view the image on a large screen, smart TVs receive the image just the same: Android TV and Google TV accept the cast button, Samsung TVs receive Smart View, and several brands are compatible with AirPlay.
And what about the "projector" apps on the Play Store?
No app can turn your phone into a projector. The screen doesn't emit enough light, nor does it have a lens to form an image at a distance. Apps with that name are either toy simulators or serve as remote controls for real projectors. The cardboard box with a magnifying glass, famous in videos, does form an image, but it's weak and only in total darkness.
Which one to choose?
Projector with Wi-Fi: mirror directly from your phone. Projector with only HDMI: Chromecast or cable, depending on your device. For presentations at work, the cable is the most reliable; for movies on the couch, wireless transmission leaves your phone free in your hand.
