问题描述
我有一个很简单的设置在这里，Xcode给我一个无评论的红色！
I have a pretty simple set up here, and Xcode is giving me a comment-less red "!" mark in the interface builder.
从基于Core Data的文档模板开始。文档xib有一个NSObjectController实例，其受管对象上下文绑定到文件的所有者（我的NSPersistentDocument子类）。一个NSTextField是存在的，其值我想绑定到NSObjectController ...这是问题所在。
Started from a Core Data-based document template. The document xib has an NSObjectController instance, whose Managed Object Context is bound to the File's Owner (my NSPersistentDocument subclass). An NSTextField is present, whose Value I want to bind to the NSObjectController...and this is where the problem comes in.
我键入标题为模型Key Path，因为这是我的NSManagedObject的正确属性，它应该出现在文本字段中。当我点击空的Controller Key字段时，自动完成建议仅用于 NSArrayController 的字段：
I type "title" for the "Model Key Path," because that's the correct property for my NSManagedObject, which should appear in the text field. When I click into the empty Controller Key field, the autocompletion bizarrely suggests fields that are only for NSArrayController:
每次尝试键入content作为控制器键（因为这是NSObjectController的正确属性），然后点击Tab / Return /无论什么，content被移动到模型键路径，如下：
Any time I try to type "content" as the Controller Key (because that's the correct property for an NSObjectController) and then hit Tab/Return/whatever, the "content" is shifted down to the Model Key Path, like so:
这是红色感叹号？当我离开控制器键空和模型键路径作为content.title，该应用程序工作。绑定是正确的，反映了我的NSManagedObject的title属性。我绝对确定对象控制器是NSObjectController的一个实例。
What is this red exclamation mark for? When I leave "Controller Key" empty and "Model Key Path" as content.title, the app works. The binding is correct and reflects the "title" property of my NSManagedObject. I am absolutely sure that "Object Controller" is an instance of NSObjectController.
推荐答案
使用选择。对于 NSObjectController ，选择是内容对象。
Use "selection". For an NSObjectController, the selection is the content object.
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