添加coredata 出现 is a forward declaration 错误So open up Xcode and look for some file like App_Pre
添加 coredata 出现 is a forward declaration 错误
So open up Xcode and look for some file like App_Prefix.pch, by default it's in the Other Sources group. After the UIKit import statement, add the following line:#import <CoreData/CoreData.h>需要在 .pch文件中加入#import <CoreData/CoreData.h>