PSoC Designer provides User Modules like DACs, Timers etc. which can be used to build a system to generate a sine wave signal. DAC is updated at regular intervals of time with a digital value stored in a look up table (contains digital data to represent a sine wave). By updating the DAC at different rate, signals of different frequency can be obtained.
Attached project and document explains how to implement such functionality using CY8C29466 device.