Steve Jobs did not agree at all to work on iPhone with an stylus since the first model back then in June 29, 2007.
The stylus is not coming at this time to the iPhones but to a new BIG iPad Pro that comes with an Apple Pencil for to take notes, draw etc.
Both the iPad Pro and the Apple Pencil will be available on November 2015.
On the videos below you can see the introduction of the iPad Pro and how the Apple Pencil works on it:
iPad has always offered a uniquely immersive experience. Now, with its 12.9-inch Retina display, powerful A9X chip, and dynamic four speaker audio, iPad Pro lets you be more creative and more productive —at an entirely new scale.
Apple Pencil is designed to look and feel like a familiar tool. Yet with its meticulously engineered technology, working with our most advanced Multi-Touch display, it delivers an extraordinary new level of precision.