I'm migrating to use the UIActivityViewController for sharing in iOS6, but I can't figure out how to create email attachment objects to be included when sharing by email.
The corresponding code in iOS5 is:
MFMailComposeViewController *picker = [[MFMailComposeViewController alloc] init];
[picker addAttachmentData:data mimeType:@"application/XXX" fileName:fileName];
You have very limited control over UIActivityViewController, but if you're attaching well-know mime types, I found you can get it to work correctly by providing the associated file extension in a file URL. For example, if your attachment is a vCard, use the ".vcf" extension in the file URL:
NSString *docsPath = [NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES) objectAtIndex:0];
// The file extension is important so that some mime magic happens!
NSString *filePath = [docsPath stringByAppendingPathComponent:@"vcard.vcf"];
NSURL *fileUrl = [NSURL fileURLWithPath:filePath];
[data writeToURL:fileUrl atomically:YES]; // save the file
// Now pass the file URL in the activity items array
UIActivityViewController *avc = [[UIActivityViewController alloc] initWithActivityItems:
@[@"Here's an attached vCard", fileUrl] applicationActivities:nil];
[vc presentModalViewController:avc animated:YES];