HTML Rendering

HTML Rendering

The three subclasses of MCOAbstractMessage (MCOIMAPMessage, MCOMessageParser, MCOMessageBuilder) each have html rendering APIs. HTML rendering of emails is actually a pretty complex operation. Emails come in many shapes and forms, and writing a single rendering engine for every application is difficult, and ultimately constricts you as the user. Instead, MailCore 2 uses HTML rendering delegates that you can use to compose a single html body out of a (potentially) complicated body structure.

The system as it is renders HTML in a generic format that should suit most purposes. You can get a rendered HTML version of the email to display to the user with one of the message classes with (example uses MCOMessageParser, though the other two children of MCOAbstractMessage work similarly):

NSString *msgHTMLBody = [messageParser htmlRenderingWithDelegate:nil];

Appendix: Customizing Rendering

Although you likely will not need to, you can customize rendering HTML from a MCOAbstractMessage subclass (MCOMessageParser, MCOIMAPMessage, MCOMessageBuilder), by implementing the MCOHTMLRendererDelegate protocol. For each body part or attachment, you provide a delegate method that is able to provide a template, and the data to fit in that template. For example, here is one method pair for the main header:

- (NSString *)renderedHTMLWithParsedMessage:(MCOMessageParser *)parser {
    return [messageParser htmlRenderingWithDelegate:self];
}

- (NSString *) MCOAbstractMessage:(MCOAbstractMessage *)msg templateForMainHeader:(MCOMessageHeader *)header {
    return @"<div style=\\"background-color:#eee\\">\
    <div><b>From:</b> {{FROM}}</div>\
    <div><b>To:</b> {{TO}}</div>\
    </div>";
}

- (NSDictionary *)MCOAbstractMessage:(MCOAbstractMessage *)msg templateValuesForHeader:(MCOMessageHeader *)header {
    NSMutableDictionary *templateValues = [[NSMutableDictionary alloc] init];
    
    if(header.from) {
        templateValues[@"FROM"] = header.from.displayName ?: (header.from.mailbox ?: @"N/A");
    }
    
    if(header.to.count > 0) {
        NSMutableString *toString = [[NSMutableString alloc] init];
        for(MCOAddress *address in header.to) {
            if(toString.length > 0) {
                [toString appendString:@", "];
            }
            [toString appendFormat:@"%@", address.displayName ?: (address.mailbox ?: @"N/A")];
        }
        templateValues[@"TO"] = toString;
    }
    
    return templateValues;
}

As you can see, we use ctemplates in order to format and insert the data we want to display in different parts of the message.