核心数据在第二视图控制器中显示多对多关系数据

I am fairly new to this, so please bare with me, my core data model look like this 2 entities with the 1st TableViewController displaying the districts, and when user selected the district, it pushes to the 2nd view and display the schools in that district. I have the 1st TableViewController with the NSFetchedResultController setup and display correctly entityForName @"District" , but I am currently stuck and failing on pushing the data to the 2nd view controller which has a custom table cell controller. I am fairly new to this, so please bare with me