The common undefined symbol error appearing while integrating test flight will be something like the following :
Undefined symbols for architecture armv7s:
“_deflateInit_”, referenced from:
_compress_data in libTestFlight.a(tf_compression.o)
“_deflateEnd”, referenced from:
_compress_data in libTestFlight.a(tf_compression.o)
“_deflate”, referenced from:
_compress_data in libTestFlight.a(tf_compression.o)
ld: symbol(s) not found for architecture armv7s
clang: error: linker command failed with exit code 1 (use -v to see invocation)
The fix for this issue is simple.
Goto the build phases of the target for which the issue is appearing. In the link binary with libraries section, use the ‘+’ button at the bottom to add a new library. In the dialog box which appears, search for libz.dylib . You will see the library in the list. Select that and press the ‘Add’ button.
Now perform a build clean for the project and you are done.
Build the app and the issue will be fixed.