While there are a lot of instructions available on the web on how to go about transferring info, this, i believe, is the fastest way you can have your contacts transferred from one device to another.
Download the "Bump" app to your android device then run the app. Its free so don't worry. In this example, the android device will be our recipient. Just leave the app running.
On to your iphone, download the app from the AppStore as well. Run the app.
Just tap OK.
This will be your home screen. You can basically input your details by tapping on the edit (pencil) button. But you don't really need to input everything now. You can skip this just like i did
Swiping left would bring you to the photos screen. So obviously, this also works with photos.
Another swipe to the left would show you this screen. Surprise surprise, it can also transfer videos and audio files.
Another swipe brings you to the contacts page, which is our main topic. If you wish to select all contacts for transfer, then just go ahead and tap on "select all". You can also transfer selectively.
Here's the screen with the select all function. All you need to do now is to bump the devices together which will be shown on the next slide.
Here's the final step.
So far, when i checked for the integrity of the transferred contacts, it contains every info i had from the original device (postal/email address, birthdays, etc).
By the way, the app can transfer from: Apple to Apple; Android to Android; Apple to Android and vice versa. I am in no way connected to the developers of this app. I hope you enjoyed this guide.