Read SMS message in iOS

1. No, there is no way to read SMS messages. Apple is very strict on this due to privacy concerns.
2. Log in to the developers portal and click App Store Review Guidelines.

Nowhere in the guidelines does it specify that you can't access the SMSes. But you can only access if you use private methods which is not allowed and will get your app rejected.

You can only access data for which Apple supplies a documented API. You can not access files outside of the Sandbox of your App unless Apple provides an API for it.

From iOS 12 Apple will supports Password AutoFill on UITextField, UITextView, and any custom view that adopts the UITextInput protocol. System keyboard set the textContentType on it to .oneTimeCode

• Using storyboard/XIB

Select UITextField/UITextView in storyboard/XIB click Click on Attribute inspector. Go to text input trait, click to Content type and select one time code and done.

It only works with System keyboard. So avoid using the custom keyboard.

And for more information, you will also review WWDC 2018 Session 204 - Automatic Strong Passwords and Security Code AutoFill and jump to 24:28 for automatic pre-fill the OTP.

UPDATE

From iOS 12 Apple has given support to read the security code (OTP - One Time Passwords) in text fields.

oneTimeCode

Specifies the expectation of a single-factor SMS login code.

You can autocomplete security codes from single-factor SMS login flows:

yourSingleFactorCodeTextField.textContentType = .oneTimeCode

iOS supports Password AutoFill on UITextField, UITextView, and any custom view that adopts the UITextInput protocol.

Warning

If you use a custom input view for a security code input text field, iOS cannot display the necessary AutoFill UI.

Support - Since iOS 12

Flow, Automatically fill in SMS passcodes on iPhone - https://support.apple.com/en-in/guide/iphone/iphc89a3a3af/13.0/ios/13.0

Implementation Guide - https://developer.apple.com/documentation/security/password_autofill/enabling_password_autofill_on_a_text_input_view

When you sign in to some apps and websites, a one-time SMS passcode is sent to your iPhone. As a security measure, you are required to enter the code into the app or website. iPhone can detect the passcode in Messages and display it above the keyboard.

To use the passcode, tap it.