删除错误的最好方法是: 1)选择类文件(.m) 2)在“目标会员”下，“勾选”项目名称条目

In my case I got this error because I'd tried to save some work by creating a new project and then deleting several of the source files and copying over the source files of the same name from the working project. I also copied my MainStoryBoard file which was looking for my RootViewController. However, when I had deleted the original RootViewController and then added in the RootViewController from the previous product, evidently the Add Files operation failed to "check" the target box as suggested above. By merely visting all of the newley imported ".m" files and making sure that the target membership box was checked, all was well. I think what was happening was that the storyboard file was looking for a class that had been "excluded" from the link because the target membership was unchecked. Making sure the required files for the target are so designated in the target membership in the file inspector did the trick. Thanks Pat! (see above)

在我的例子中，问题是一个死的IBOutlet链接。一旦这个问题解决了，一切又恢复了正常。

我通过从我的class.h和.m复制文本来修复这个问题，从项目中删除这些类文件，并使用“添加文件”创建新的class.h和.m文件。然后我将代码粘贴回新文件中，一切都运行良好。由于某种原因，文件在创建时没有正确链接。在那之后，我不需要使用任何链接标志。

在我的例子中，我有XCode6，指定的类.m文件最终在构建阶段的错误位置-它应该在编译源下，但最终在

不仅在项目设置中，在目标设置中也必须添加-all_load -ObjC标志。

Core-Plot: Interface Builder文件中的未知类CPLayerHostingView