Cocoa绑定 - 为所有孩子的属性获取@sum [英] Cocoa bindings - get @sum for an attribute for all children
问题描述
我已经尝试让这个工作一段时间了。
I've been trying to get this to work for a while now.
在我的核心数据模型中,我有:
In my Core Data model I have:
实体公司
与雇员
(
)
Company.employees
Employee.age
使用绑定我想显示所有 employees
在公司
在一个tableView。
Using bindings I would like to show the sum of age for all employees
when clicking on a Company
in a tableView.
我尝试了变化: @distinctUnionOfSets .employees。@ sum.age
,但不能让它工作。
当我尝试上面的时候,我得到错误信息:
[< _NSFaultingMutableSet 0x10019c430> removeObserver:forKeyPath:]不支持。键路径:@ sum.age
I've tried variations of: @distinctUnionOfSets.employees.@sum.age
, but can't get it to work.
When I try the above I get the error message:
[<_NSFaultingMutableSet 0x10019c430> removeObserver:forKeyPath:] is not supported. Key path: @sum.age
我的 NSArrayController
绑定到 Client
所以在IB它看起来像这样: Clients.selection。@ distinctUnionOfSets.employees。@ sum.age
My NSArrayController
is bound to Client
so in IB it looks like this: Clients.selection.@distinctUnionOfSets.employees.@sum.age
任何想法?
推荐答案
添加了一个绑定到Employee的新NSArrayController。
I made this more complicated than it was. Added a new NSArrayController which was bound to Employee.
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