cocoapods dylib dependency use_frameworks

Question

I have built a dynamic library (to add ICU support in this case) which i need to add as a dependency to a pod. For that I created a pod with the following podspec (I removed things like authors, license, ... to keep it short)

Pod::Spec.new do |s|
  s.name     = 'unicode'
  s.version  = '57.0'
  s.source              = { :git => "[email protected]:mycompany/unicode.git", :tag => "#{s.version}" }
  s.requires_arc = false
  s.platform = :ios, '8.0'

  s.default_subspecs = 'all'

  s.subspec 'all' do |ss|
    ss.header_mappings_dir = 'icu4c/include'
    ss.source_files = 'icu4c/include/**/*.h'
    ss.public_header_files = 'icu4c/include/**/*.h'
    ss.vendored_libraries = 'Frameworks/lib*.dylib'
  end

end

Here i have a second pod where i need to link these libraries too

Pod::Spec.new do |s|
  s.name     = 'sqlite3'
  s.version  = '3.14.2'
  s.summary  = 'SQLite is an embedded SQL database engine'
  s.documentation_url = 'https://sqlite.org/docs.html'
  s.homepage = 'https://github.com/clemensg/sqlite3pod'
  s.authors  = { 'Clemens Gruber' => '[email protected]' }

  v = s.version.to_s.split('.')
  archive_name = "sqlite-amalgamation-"+v[0]+v[1].rjust(2, '0')+v[2].rjust(2, '0')+"00"
  #s.source   = { :http => "https://www.sqlite.org/#{Time.now.year}/#{archive_name}.zip" }
  s.source              = { :git => "[email protected]:wrthphoenixspeedy/sqlite3.git", :tag => "#{s.version}" }
  s.requires_arc = false
  s.platform = :ios, '8.0'

  s.default_subspecs = 'common'

  s.subspec 'common' do |ss|
    ss.source_files = "#{archive_name}/sqlite*.{h,c}"
    ss.osx.pod_target_xcconfig = { 'OTHER_CFLAGS' => '$(inherited) -DHAVE_USLEEP=1' }
    # Disable OS X / AFP locking code on mobile platforms (iOS, tvOS, watchOS)
    sqlite_xcconfig_ios = { 'OTHER_CFLAGS' => '$(inherited) -DHAVE_USLEEP=1 -DSQLITE_ENABLE_LOCKING_STYLE=0' }
    ss.ios.pod_target_xcconfig = sqlite_xcconfig_ios
    ss.tvos.pod_target_xcconfig = sqlite_xcconfig_ios
    ss.watchos.pod_target_xcconfig = sqlite_xcconfig_ios
  end

  # enable support for icu - International Components for Unicode
  s.subspec 'icu' do |ss|
    ss.dependency 'sqlite3/common'
    ss.pod_target_xcconfig = { 'OTHER_CFLAGS' => '$(inherited) -DSQLITE_ENABLE_ICU=1' }
    ss.dependency           'unicode', '57.0'
    ss.libraries = 'icucore', 'icudata.57.1', 'icui18n.57.1', 'icuio.57.1', 'icule.57.1', 'iculx.57.1', 'icutu.57.1', 'icuuc.57.1'
  end

end

And with these i am able to compile it. Cocoapods is copying these libraries on build time into the folder ../Frameworks/ rather than to do while on run time. Instead it fails because it says that it doesn't find the library in ../lib.

dyld: Library not loaded: ../lib/libicudata.57.1.dylib
  Referenced from: /var/containers/Bundle/Application/9663CB3A-6ACD-487E-A92D-48F8AFE5260C/MyApp.app/MyApp
  Reason: image not found

I have to use use_frameworks! because i am using some Swift frameworks too.

So i am doing something wrong... the question is, can i link a dylib from one pod to another pod? and if so... how?

Answer 1

Based on the disparity between "libs" and "Frameworks", this looks like an issue with either runpath search paths (the running app is not looking for the library from Frameworks), or with the install name of the library not matching the location where it's placed relative to where it is dynamically loaded from.

1. Make sure that in the app that bundles the dynamic library you have the following paths included in your "Runpath Search Path": @executable_path/../Frameworks, @loader_path/../Frameworks

2. Make sure that the "Dynamic Library Install Name" name of the library being loaded is set to the equivalent of @rpath/$(EXECUTABLE_PATH) (i.e. in your case it should be "@rpath/libicudata.57.1.dylib"). You can set it during build time using the -install_name compiler (linker?) flag, or with install_name_tool, like so: install_name_tool -id "@rpath/libicudata.57.1.dylib" libicudata.57.1.dylib . Hopefully doesn't come to this though.