ios - iMessage Extensions: How to specify the Email Subject or Add Text to the body of the email? -

i sending imessage imessage extension app contact has gmail address specified.

here sample piece of code reflects parameters passed:

msmessagetemplatelayout* layout = [msmessagetemplatelayout new];  layout.caption = @"my caption"; layout.trailingsubcaption = @"trailing subcaption"; layout.subcaption = @"sub caption"; layout.imagetitle = @"image title"; layout.image = image;  // now, let's make message msmessage* message = [msmessage new]; message.url = myurl; message.layout = layout;  [self.conversation         insertmessage:message         completionhandler:^(nserror * _nullable handler) {             // continue ui actions         }]; 

now, fields specified, show up, if receiving on iphone in imessage.

however, if send message email contact (no phone numbers specified in contact profile), email has: 1. no subject. 2. none of fields above, except: image , url below image.

so person unlikely click on link, because suspicious, not trust contents of email, because not personalized enough.

i need able put more personable information email, in form of subject , body text, can trust contents of email.

how can imessage's msmessage object populate email's subject line, or add text body of email. seems have explored every single field, , none of them carry through email delivery, except url , image.

i realize it's out of our developer control - determine imessage @ delivery stage, when realized email contact.