As most of you will know the iPhone can't take macro shots, those photos which are really up close showing lots of very fine detail. This just doesn't apply to the iPhone though, most phones are incapable of taking macro shots. This is because the lens on phones aren't made for macro photography, they're made for all round photography.
Now you can easily get macro lenses for your phone but if you get a cheap one it usually falls apart, or if you got a proper macro lens it can be quite expensive.
What you can do instead is add a water drop to your lens. This is a free way in which to take up close macro shots. And it actually works pretty well. This works brilliantly for the iPhone because the back plate of the iPhone is just one piece. However I'd be weary of using any other phones. I'd make sure that the cover over your camera is completely sealed because if water gets in there you're pretty much f'd.