I work with the storyboard. I have a view controller with a stack view (axis: horizontal, alignment: fill, distribution: fill equally, spacing: 10), but the spacing is not shown in the simulator. The two views of the stack views have to be equally wide. Is there any configuration, which I can change to make the spacing visible?

I used the storyboard and horizontal and vertical stack views to generate a good looking App. This worked fine, but one view does not show the Table View I placed there. In the storyboard everything is fine and no warning is shown. I tried to remove the Table View and renew it, but that did not fix the problem. Has anybody an idea what I missed ?

I am getting the same error over and over again and I do not know why. I tried several ways to fix it, but nothing works. Building native extensions. This could take a while... ERROR:  Error installing cocoapods: ERROR: Failed to build gem native extension.     current directory: /Library/Ruby/Gems/2.6.0/gems/ffi-1.13.1/ext/ffi_c /System/Library/Frameworks/Ruby.framework/Versions/2.6/usr/bin/ruby -I /Library/Ruby/Site/2.6.0 -r ./siteconf20201202-2686-t7m7nb.rb extconf.rb checking for ffi.h... * extconf.rb failed * Could not create Makefile due to some reason, probably lack of necessary libraries and/or headers.  Check the mkmf.log file for more details.  You may need configuration options. Provided configuration options: --with-opt-dir --without-opt-dir --with-opt-include --without-opt-include=${opt-dir}/include --with-opt-lib --without-opt-lib=${opt-dir}/lib --with-make-prog --without-make-prog --srcdir=. --curdir --ruby=/System/Library/Frameworks/Ruby.framework/Versions/2.6/usr/bin/$(RUBY_BASE_NAME) --with-ffi_c-dir --without-ffi_c-dir --with-ffi_c-include --without-ffi_c-include=${ffi_c-dir}/include --with-ffi_c-lib --without-ffi_c-lib=${ffi_c-dir}/lib --enable-system-libffi --disable-system-libffi --with-libffi-config --without-libffi-config --with-pkg-config --without-pkg-config /System/Library/Frameworks/Ruby.framework/Versions/2.6/usr/lib/ruby/2.6.0/mkmf.rb:467:in `try_do': The compiler failed to generate an executable file. (RuntimeError) You have to install development tools first. from /System/Library/Frameworks/Ruby.framework/Versions/2.6/usr/lib/ruby/2.6.0/mkmf.rb:585:in `block in try_compile' from /System/Library/Frameworks/Ruby.framework/Versions/2.6/usr/lib/ruby/2.6.0/mkmf.rb:534:in `with_werror' from /System/Library/Frameworks/Ruby.framework/Versions/2.6/usr/lib/ruby/2.6.0/mkmf.rb:585:in `try_compile' from /System/Library/Frameworks/Ruby.framework/Versions/2.6/usr/lib/ruby/2.6.0/mkmf.rb:1109:in `block in have_header' from /System/Library/Frameworks/Ruby.framework/Versions/2.6/usr/lib/ruby/2.6.0/mkmf.rb:959:in `block in checking_for' from /System/Library/Frameworks/Ruby.framework/Versions/2.6/usr/lib/ruby/2.6.0/mkmf.rb:361:in `block (2 levels) in postpone' from /System/Library/Frameworks/Ruby.framework/Versions/2.6/usr/lib/ruby/2.6.0/mkmf.rb:331:in `open' from /System/Library/Frameworks/Ruby.framework/Versions/2.6/usr/lib/ruby/2.6.0/mkmf.rb:361:in `block in postpone' from /System/Library/Frameworks/Ruby.framework/Versions/2.6/usr/lib/ruby/2.6.0/mkmf.rb:331:in `open' from /System/Library/Frameworks/Ruby.framework/Versions/2.6/usr/lib/ruby/2.6.0/mkmf.rb:357:in `postpone' from /System/Library/Frameworks/Ruby.framework/Versions/2.6/usr/lib/ruby/2.6.0/mkmf.rb:958:in `checking_for' from /System/Library/Frameworks/Ruby.framework/Versions/2.6/usr/lib/ruby/2.6.0/mkmf.rb:1108:in `have_header' from extconf.rb:10:in `system_libffi_usable?' from extconf.rb:42:in `<main>' To see why this extension failed to compile, please check the mkmf.log which can be found here:   /Library/Ruby/Gems/2.6.0/extensions/universal-darwin-19/2.6.0/ffi-1.13.1/mkmf.log extconf failed, exit code 1 Gem files will remain installed in /Library/Ruby/Gems/2.6.0/gems/ffi-1.13.1 for inspection. Results logged to /Library/Ruby/Gems/2.6.0/extensions/universal-darwin-19/2.6.0/ffi-1.13.1/gem_make.out Something might be wrong with Ruby, but I could not figure out what I should do to fix it.