Xcode compilation undefined symbols for architecture XXX error

Undefined Symbols for Architecture armv7
Undefined Symbols for Architecture armv7s
Undefined Symbols for Architecture arm64
Undefined Symbols for Architecture i386
Undefined Symbols for Architecture x86_64

When multiple people work together on the same project or copy a project, there are often problems like this:

Undefined Symbols for Architecture XXX:

"_objc_class_$_xx file name", referenced from:

There are probably the following 4 kinds of possible, the first three kinds of online many people have said, and the fourth situation is recently trapped around, if the first three methods can not be resolved after the use, you may consider the fourth possible;

1. Related project files not imported

You can directly in here + come in, you can also in the left engineering directory to all re-guide the document (in the case of multi-person operation of the project, the general approach)

2..framework File not imported

Put xx file library + come in, this question "_objc_class_$_asidentifiermanager", is because Adsupport.framework class library does not add

3. File path missing

Check if some file paths are not joined or are incorrectly written

4. Objects in the file you are prompted to create an object of the non-implemented class

This situation is due to coding personnel errors, only the function or class is declared in the. h file, but not implemented in the corresponding. m or. cpp file;

If you can check the code, or fragment comment on the suspicious part, to see if it will also be prompted, corrections are generally easy, but it is difficult to associate with the compilation error.

Xcode compilation undefined symbols for architecture XXX error