NSSortDescriptor在Swift中使用NSDate进行排序

如何使用该受管对象的date属性对NSFetchRequest进行排序.那么它创建一个数组,其日期顺序？

这是我的代码到目前为止

var request : NSFetchRequest = NSFetchRequest(entityName: "History");
    request.predicate = nspredicate(format: "counts = %@",true)
    request.sortDescriptors = [???] <- What should I put here?
    var results : [NSManagedobject] = context.executeFetchRequest(request,error: nil) as [NSManagedobject]

// newest first
request.sortDescriptors = [NSSortDescriptor(key: "date",ascending: false)]

注意：您不需要：[NSManagedobject]如果您已经具有[NSManagedobject].当您使用NSFetchRequest的工厂方法时,您不需要：NSFetchRequest.