Opening URL from Today Extension

Question

I am developing a cocoa app which is also using a Today extension for OSX Yosemite.

I have a button on the Today extension and I need it to open the main browser and a defined website.

I normally use

[[NSWorkspace sharedWorkspace] openURL:[NSURL URLWithString:@"http://www.google.com"]];

but this code is not working when it's used in the extension.