Mobile app Developer

We want to create a few functionality in a mobile app which is already available in our cloud based software which is developed in core PHP and my sql .For your understanding I just give you a quick view of our software functionality to you to understand more. The company do services to their customers. The company capture all services given by their client as jobs. Each job have multiple task. They will allocate the task to their employee. They can allocate multiple jobs and multiple task to the employee at a time. Each day the employee has to enter his time sheet. Each employee have their own user name and password. We want to recreate this time sheet entry and few other features which I describe below in mobile app.