We demonstrate a frequency-tunable superconducting coplanar waveguide resonator, with a tuning range of half a gigahertz and a switching time of 1 ns. The resonator is made tunable by inserting a superconducting quantum interference device in the center strip of the resonator. Quantum measurements are made by probing the resonator with a superconducting qubit, allowing us to use microwave photon Fock states to benchmark the resonator performance. Using the resonator, we shuttle energy quanta between the qubit and a microscopic two-level state. The tunable resonator can, therefore, serve as a communication bus or memory element in a prototype quantum processor.