Since there’s no direct way for you to transfer calendar from Android phones like Samsung to iPhone, you may wish to find another simple method to finish this job quickly,maybe the third party software is a good choice for you.
FoneDog Phone Transfer lets you transfer data between different phones with one click, including iOS, Android, Symbian, and Win Phone. You can use it to transfer data between any of them.Next, let's check how to use Phone Transfer- Phone to Phone Transfer in steps.
Step 1. Connect your device to the computer
Open the transfer software, and click on "Phone to Phone Transfer". Then get both of your devices connected. Here let's take an iOS and an Android device as an example.
The data will be transferred from the source device to the destination one. You can use the "Flip" button to exchange their position.
Step 2. Choose the file and start to transfer
Check the files you would like to transfer. Then click on "Start Transfer" to begin the process. For efficiency, don’t disconnect the devices until the process is complete.
Note: You can check the "Clear Data before Copy" box if you want to erase data on the destination phone before copying the new data.
Hope you can benefit from the article above.

Unfortunately the latest version of iTunes (v11) doesn't allow syncing contact with Google services .... Good one apple.
That just about does it for me. Happy to leave the apple world in my wake

The easiest way is to sync your iPhone with Google. This will transfer all of your contacts, calenders etc to your Google Account, and your Galaxy will sync all of this data automatically.
Once you've performed a single sync on your iPhone, you can wipe your iPhone.
There is also solution about How to Transfer Contacts between Samsung and iPhone.
Hope this helps. Good Luck!

You can transfer your contacts from the iPhone to your Samsung Galaxy SIII by using iTunes and Google/Gmail sync. You only need to have the latest version of iTunes installed on your computer and a Gmail account.

Synchronizing Your Contacts from the iPhone to Gmail via iTunes

1. Make sure you have the latest version of iTunes installed
2. On your computer, open iTunes.
3. Then connect your iPhone to the computer via the USB cable.
4. From your devices list on iTunes, select the iPhone.
5. In case you are syncing and backing up your data using iCloud, change that to using your PC.
6. Then click on the Info tab.
7. You’ll see a Sync Contacts with option, click on that and select either Google Address Book Contacts or Google Contacts.
8. In the Google ID field -> enter your gmail address.
9. In the Password field -> enter your password.
10. Then click OK.
11. Your iPhone will be synchronized.

Since the Galaxy SIII is an Android device, Google sync should be enabled by default, thus your contacts should populate in just a few minutes.

In case your contacts are not synchronized after a few minutes, then follow the next steps to add an email account and enable syncing:

1. From the Home screen, open the Notification panel and tap Settings (gear in the upper right).
2. Then go to Accounts -> Add account and select the account type you wish to add. In our case it would be Google.
3. Then just follow the on-screen steps to enter the necessary account information.
4. And that’s it! You should now have the contacts from your iPhone transferred to your Galaxy SIII!