Pipe standard output to a running Cocoa app

gistfile1.txt

1) Create a script named '~/bin/xscope':

#!/bin/sh

parameter=""
if [ -z "$1" ]; then
    parameter=`cat /dev/stdin`
else
    parameter="$1"
fi

if [ ! -z "$parameter" ]; then
    open "xscope://text/$parameter"
fi

2) In the Cocoa app, register for the AppleEvent sent by 'open' when the application delegate starts up:

- (void)setUpEventHandlerForURL
{
	[[NSAppleEventManager sharedAppleEventManager] setEventHandler:self
                                                       andSelector:@selector(getURLFromEvent:withReplyEvent:)
                                                     forEventClass:kInternetEventClass
                                                        andEventID:kAEGetURL];
}

3) Handle the URL event:

- (void)getURLFromEvent:(NSAppleEventDescriptor *)event withReplyEvent:(NSAppleEventDescriptor *)replyEvent
{
	NSString *URLString = [[event paramDescriptorForKeyword:keyDirectObject] stringValue];
	
	NSURL *URL = [NSURL URLWithString:URLString];
	if ([[URL host] isEqualToString:@"text"]) {
		NSString *path = [URL path];
		if (path && [path length] > 0) {
			NSString *encodedParameter = [path substringFromIndex:1];
			NSString *textParameter = [encodedParameter stringByReplacingPercentEscapesUsingEncoding:NSUTF8StringEncoding];
			DebugLog(@"textParameter = %@", textParameter);
		}
	}
}

4) Finally, add this to your Info.plist:

	<key>CFBundleURLTypes</key>
	<array>
		<dict>
			<key>CFBundleURLName</key>
			<string>xScope URL scheme</string>
			<key>CFBundleURLSchemes</key>
			<array>
				<string>xscope</string>
			</array>
		</dict>
	</array>

5) Now pipe output to the app using:

$ cal | ~/bin/xscope

or by using a parameter:

$ ~/bin/xscope $'\xf0\x9f\x8d\x94'

Please don’t use scheme:// for non-RFC 1808 URI schemes.

What's the problem?

The use of :// is conventionally reserved for URIs that take the form <scheme>://<net_loc>/<path>;<params>?<query>#<fragment>. The // serves no other purpose than to signify that the scheme conforms to that pattern. To keep generic tools – like NSURL – working as intended, use scheme:foo without // for URIs that don’t.