The iPhone is a collection of modules, chips, and electronic components from different manufacturers. Due to the complexities of the iPhone, the list of hardware components is extensive and each device should be researched for internal components.
The following images show the internals of iPhone 6. The images were taken after dismantling the iPhone 6. Internal images for all iPhones can be found in the teardown section at http://www.ifixit.com/Device/iPhone.
The following is the image shows the back of the iPhone 6: