This is a quick tutorial on how to apply a halftone to live text in Illustrator. What’s great about this one is that it opens up so many possibilities in regards to live text effects in Illustrator. I’ll provide some further examples at the end.
1. Start by making some text, A thicker typeface at a large scale works best for this. I used the Font Impact at 72pts.
2. With the type still selected, open the Appearances Panel from the WINDOW menu. From the Appearance Panel menu, select Add New Fill
3. Click on the icon for the new fill and apply the White to Black gradient.
4. If you want to adjust the Gradient, click on the gradient tool 
on the toolbar and redraw the overall length of the gradient. With this effect, everything is “live” meaning you can adjust this after you apply the halftone effect in the next step.
5. With the type still selected click on the FX icon at the bottom of the Appearances Panel and go to the Raster effects (effects that come from the Photoshop side of image manipulation), click on the Pixelate submenu and then Color Halftone.
The color halftone effect mimics the appearance of 4 color printing that is used for magazines, posters, postcards etc..The color halftone uses 4 colors (Cyan, Magenta, Yellow, and Black) of dots in various sizes, to simulate continuous tone images. For this part of the tutorial, however, we want to make the dots one color, black. In the Color Halftone Panel, change the angle for each channel to 45 degrees and make the Max Radius 12 pixels.
6. Because this effect is live we can change all of these parameters.
7. Here are some other things to try with this effect: Make a uniform halftone by changing the fill color to a solid gray.
A lighter shade of gray will make the dots smaller
Add a second fill above the halftone fill, change the swatch to a color and the under Opacity change the blend mode to Multiply
You can also try a full-color halftone, by changing the gradient to a spectrum gradient and providing different angles for the halftone channels. Go to the WINDOW menu > SWATCH LIBRARIES > GRADIENT > SPECTRUMS and with the text selected choose your gradient. With the text still selected click on the halftone fx in the Appearances List (or reapply it if you are restarting this effect – see step 6) and provide the following angles Channel 1: 15, 2:75, 3: 0, 4:45.
As with most things in Illustrator, the possibilities are limitless. Have Fun!