(Objective-C) The MIME Content-Type Header Field

Explains the ContentType property and the Content-Type header field including the various attributes that may be included.

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#import <CkoMime.h>

// Every part in a MIME messsage should include a Content-Type header field.
// The Content-Type indicates the type of content contained in the MIME part.
// For example: text/plain, image/jpeg, application/pdf, application/json, multipart/mixed, etc.

// Multipart content types are those where the MIME part's body is composed of N inner MIME messages,
// separated by a boundary string.
// This is how MIME gets a nested, tree-like structure.  The most common multipart MIME types
// are (for email related MIME) multipart/mixed, multipart/alternative, and multipart/related,
// and for HTTP related MIME, it is multipart/form-data.

BOOL success;
CkoMime *mime = [[CkoMime alloc] init];

// The Content-Type header field can be set or modified in two ways.
// 1) By setting the ContentType, Micalg, Name, Charset, Boundary, or Protocol properties.
//    Setting the ContentType property sets the primary value (such as "text/plain") of the header field.
//    Each of the other properties listed above will replace or add a particular attribute value.

// 2) By setting the entire contents of the ContentType header with the SetHeaderField method.
//    This updates each of the Content-Type related properties.

// For example:
mime.ContentType = @"text/plain";
mime.Charset = @"utf-8";

// The Content-Type header field contains this:
//     Content-Type: text/plain; charset=utf-8
NSLog(@"%@",[mime GetEntireHead]);
NSLog(@"%@",@"-");

[mime SetHeaderField: @"Content-Type" value: @"image/jpeg; name=\"kitty.jpg\""];
// The Content-Type header field now contains this:
//     Content-Type: image/jpeg; name="kitty.jpg"
NSLog(@"%@",[mime GetEntireHead]);
NSLog(@"%@",@"-");

// Notice how the properties have been updated:
NSLog(@"%@%@",@"ContentType property: ",mime.ContentType);
NSLog(@"%@%@",@"Charset property: ",mime.Charset);
NSLog(@"%@%@",@"Name property: ",mime.Name);
NSLog(@"%@",@"-");

// To change a particular attribute value, set the property.
mime.Name = @"doggy.jpg";
NSLog(@"%@",[mime GetEntireHead]);
NSLog(@"%@",@"-");

// To remove an attribute value from the Content-Type header,
// set the property to an empty string.
mime.Name = @"";
NSLog(@"%@",[mime GetEntireHead]);
NSLog(@"%@",@"-");