How to switch between SMS and MMS sent by iphone?

When sending a message, select "Insert Contact" and the message will be sent as a multimedia message (attachment). It can be operated by the following methods: information-writing information-editing content interface, click the menu button in the lower left corner of the mobile phone, and select "Add Text"-Contacts-Select Related Contacts Add-Send.

Only the text in MMS can be transferred out, as follows: Select Forward in SMS interface, and then copy the text directly.