$ pod install 
Analyzing dependencies
dyld: lazy symbol binding failed: Symbol not found: _ffi_prep_closure_loc
  Referenced from: /usr/local/lib/ruby/gems/2.7.0/gems/ffi-1.14.2/lib/ffi_c.bundle
  Expected in: /usr/lib/libffi.dylib

dyld: Symbol not found: _ffi_prep_closure_loc
  Referenced from: /usr/local/lib/ruby/gems/2.7.0/gems/ffi-1.14.2/lib/ffi_c.bundle
  Expected in: /usr/lib/libffi.dylib

Abort trap: 6

解决方案:

gem install ffi -- --disable-system-libffi