Intercept mailto URLs in a UIWebView and send them to a MFMailComposeViewController

WebViewController.m

- (BOOL)webView:(UIWebView *)webView shouldStartLoadWithRequest:(NSURLRequest *)request navigationType:(UIWebViewNavigationType)navigationType {
	
	if ([[[request URL] scheme] isEqualToString:@"mailto"]) {
		MFMailComposeViewController *mailViewController = [[MFMailComposeViewController alloc] init];
		mailViewController.mailComposeDelegate = self;

		NSArray *rawURLparts = [[[request URL] resourceSpecifier] componentsSeparatedByString:@"?"];
		if (rawURLparts.count > 2) {
			return NO; // invalid URL
		}
		
		NSMutableArray *toRecipients = [NSMutableArray array];
		NSString *defaultRecipient = [rawURLparts objectAtIndex:0];
		if (defaultRecipient.length) {
			[toRecipients addObject:defaultRecipient];
		}
		
		if (rawURLparts.count == 2) {
			NSString *queryString = [rawURLparts objectAtIndex:1];
			
			NSArray *params = [queryString componentsSeparatedByString:@"&"];
			for (NSString *param in params) {
				NSArray *keyValue = [param componentsSeparatedByString:@"="];
				if (keyValue.count != 2) {
					continue;
				}
				NSString *key = [[keyValue objectAtIndex:0] lowercaseString];
				NSString *value = [keyValue objectAtIndex:1];
				
				value =  (NSString *)CFURLCreateStringByReplacingPercentEscapesUsingEncoding(kCFAllocatorDefault,
																							 (CFStringRef)value,
																							 CFSTR(""),
																							 kCFStringEncodingUTF8);
				[value autorelease];
				
				if ([key isEqualToString:@"subject"]) {
					[mailViewController setSubject:value];
				}
				
				if ([key isEqualToString:@"body"]) {
					[mailViewController setMessageBody:value isHTML:NO];
				}
				
				if ([key isEqualToString:@"to"]) {
					[toRecipients addObjectsFromArray:[value componentsSeparatedByString:@","]];
				}
				
				if ([key isEqualToString:@"cc"]) {
					NSArray *recipients = [value componentsSeparatedByString:@","];
					[mailViewController setCcRecipients:recipients];
				}
				
				if ([key isEqualToString:@"bcc"]) {
					NSArray *recipients = [value componentsSeparatedByString:@","];
					[mailViewController setBccRecipients:recipients];
				}
			}
		}
		
		[mailViewController setToRecipients:toRecipients];

		[self presentModalViewController:mailViewController animated:YES];
		[mailViewController release];
		return NO;
	}
	return YES; 
}

If you're on Stackoverflow, vote it up: http://stackoverflow.com/questions/4125532/readymade-solution-to-parse-mailto-urls-in-cocoa

You could add a direct link to your answer on SO: http://stackoverflow.com/a/4126204/377384

Changing line 30 to
value = [value stringByReplacingPercentEscapesUsingEncoding:NSUTF8StringEncoding];
Should make it ARC friendly... Also it seems to handle HTML body data as well (at least an embedded link I have) so optionally isHTML can be turned to YES. Optimally you would check the body content for HTML and then toggle as needed... but that's more than I need.