first put a breakpoint (remember global breakpoints, so you can detect when something breaks) and then I know that my own class is writing
TTCourse *course=[[TTCourse alloc]init]; This is a problem, after is – [TTCourse setCourseID:] : unrecognized selector that sent to instance 0 x7fa392ecb080 this mistake, and then I looked at it inherited type is NSManagedObject, so initialization must use this type of initialization, namely insertNewObjectIntoContext this method.
TTCourse *course = [TTCourse insertNewObjectIntoContext:[TTImporter sharedInstance].context]; [TTImportersharedInstance].0 context. You can just write your own context.
Also, here’s a more recognized selector sent to instance
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