BLE Connection

I am trying to use BLE in Flutter. I have the following three questions regarding BLE connections:

  1. At what point in iOS is the ATT MTU negotiation considered complete after a BLE connection is established?

  2. Is there an official callback or state that indicates the completion of the negotiation?

  3. Is the value used by iOS during ATT MTU negotiation fixed? If it is fixed, please tell me that value; if it varies, please tell me the conditions under which it varies.

If anyone knows the answer, please let me know.

BLE Connection
 
 
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