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)

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

转到构建阶段->编译源代码并添加新的。m文件。

转到“ProjectName”，点击它，然后进入“Build phases”选项卡，然后点击“compile sources”，然后点击“+”按钮，一个窗口将出现，选择“MyClass”。然后点击“添加”，

建立项目并运行它，问题一定会得到解决

在我的情况下，我得到这个错误消息由一个非常愚蠢的错误由我:在接口构建器上，我想设置一个UITableViewCell的标识符，但我意外地键入标识符到'自定义类'的接口构建器条目。

我在....之前制造了1000次细胞

在我的例子中是一个拼写错误的“自定义类”名称。确保您检查了您所定义的自定义类的故事板。