Linker command failed with exit code 1), linkerfailed

Linker command failed with exit code 1), linkerfailed

This error occurs when a third-party library is imported.

1. The import file is missing, including the XXXX. a file or the system framework file.

2. Duplicate File Import, especially ViewController. If two viewcontrollers with the same name are imported, this error will be reported during alloc because the system does not know which alloc file is required,

I encountered this problem today, which is the second type. There may be more cases. I will try again later to add this error.