If you are looking for free iOS 8 tab bar icons, then IconBeast Lite is one of the best sets out there.
IconBeast Lite contains 200 free iOS 8 Tab Bar icons in 30×30 pixels that are saved in individual PNG transparency. These PNG icons are all ready to be used in your project. IconBeast Lite is published under Creative Common License (with attribution). You can use them in your own projects or client’s projects.
However, if these 200 iOS 8 icons are not enough for your project, try checking out the full version IconBeast Pro which contains more than 3000 icons.