我可以断言NSMutableArray自定义对象（NSObject）吗？

Question

如何从可变自定义对象数组中获取特定的自定义对象？

class College : NSObject{
    var id = String()
    var name = String()
}

let arrOfObjs = NSMutableArray()
let objOfCollege = College()
objOfCollege.id = "1"
objOfCollege.name = "kiran"
arrOfObjs.append(objOfCollege)
let objOfCollege1 = College()
objOfCollege1.id = "2"
objOfCollege1.name = "Lakshmi"
arrOfObjs.append(objOfCollege1)
let predicate = NSPredicate(formate: "id == %@", "2")
let newArrObj = arrOfObjs.filtered(using: predicate) as NSArray

newArrObj每次都崩溃。