How do you make a black light from an iPhone?

To create a black light effect using an iphone, you can use a blue or violet filter over the flashlight. A simple method is to use a piece of blue cellophane or a similar translucent material, cutting it to fit over the iphone's flashlight. Additionally, there are apps available that can enhance the flashlight's color output to simulate a black light. However, keep in mind that this DIY method won't produce the same UV light as a true black light.