如何通过编程方式设置应用程序的锁或pin

So right now I am trying to develop an Android App for my young children. I want to set a pin or passwords on selected applications for a particular amount of time to prevent them from opening the app. For example, let's say that my daughter wants to play angry birds for some time on my phone while I am doing work. I will select my important apps like messaging, gmail, etc and put a pin or password on it for 30 minutes while she plays angry birds. After 30 minutes, I get my phone from my daughter and I can open the app without a pin because the time limit expired. So right now I am trying to develop an Android