Use correct link to Apple Platform Security Guide

The previous link is not valid anymore

mobile-pentesting/ios-pentesting/ios-basics.md

@@ -37,7 +37,7 @@ When a **file is created** on the disk, a new **256-bit AES key is generated** w
 
 For decrypting the file, the **metadata is decrypted using the system's key**. Then u**sing the class ID** the **class key is retrieved** **to decrypt the per-file key and decrypt the file.**
 
-Files can be assigned to one of **four** **different** **protection** classes, which are explained in more detail in the [iOS Security Guide](https://www.apple.com/business/docs/iOS\_Security\_Guide.pdf):
+Files can be assigned to one of **four** **different** **protection** classes, which are explained in more detail in the [Apple Platform Security Guide](https://help.apple.com/pdf/security/en_US/apple-platform-security-guide.pdf):
 
 * **Complete Protection (NSFileProtectionComplete)**: A key derived from the user passcode and the device UID protects this class key. The derived key is wiped from memory shortly after the device is locked, making the data inaccessible until the user unlocks the device.
 * **Protected Unless Open (NSFileProtectionCompleteUnlessOpen)**: This protection class is similar to Complete Protection, but, if the file is opened when unlocked, the app can continue to access the file even if the user locks the device. This protection class is used when, for example, a mail attachment is downloading in the background.