How can I modify OTHER_LDFLAGS via CocoaPods post-install hook?

I stumbled across the same problem. First I tried to modify OTHER_LDFLAGS with the obvious:

post_install do |installer|
    installer.pods_project.targets.each do |target|
        if target.name == "Pods-SomeTarget"
            puts "Updating #{target.name} OTHER_LDFLAGS"
            target.build_configurations.each do |config|
                config.build_settings['OTHER_LDFLAGS'] ||= ['$(inherited)']
                config.build_settings['OTHER_LDFLAGS'] << '-l"AFNetworking"'
            end
        end
    end
end

but it didn’t work. The relevant xcconfig didn’t get the change. Eventually I found a workaround that works well – first read the relevant xcconfig file content in the post_intall hook, modify it and write it back:

v1.0

post_install do |installer|
    installer.pods_project.targets.each do |target|
        if target.name == "Pods-SomeTarget"
            puts "Updating #{target.name} OTHER_LDFLAGS"
            target.build_configurations.each do |config|
                xcconfig_path = config.base_configuration_reference.real_path
                xcconfig = File.read(xcconfig_path)
                new_xcconfig = xcconfig.sub('OTHER_LDFLAGS = $(inherited)', 'OTHER_LDFLAGS = $(inherited) -l"AFNetworking"')
                File.open(xcconfig_path, "w") { |file| file << new_xcconfig }
            end
        end
    end
end

EDIT: Improvement over the v1.0. Instead of operating on xcconfig String content directly, read xccconfig into a build_configuration Hash, modify the hash and then flush it to xcconfig.

v1.5

post_install do |installer|
    installer.pods_project.targets.each do |target|
        if target.name == "Pods-SomeTarget"
            puts "Updating #{target.name} OTHER_LDFLAGS"
            target.build_configurations.each do |config|
                xcconfig_path = config.base_configuration_reference.real_path

                # read from xcconfig to build_settings dictionary
                build_settings = Hash[*File.read(xcconfig_path).lines.map{|x| x.split(/\s*=\s*/, 2)}.flatten]

                # modify OTHER_LDFLAGS
                build_settings['OTHER_LDFLAGS'] << '-l"AFNetworking"'

                # write build_settings dictionary to xcconfig
                build_settings.each do |key,value|
                  File.open(xcconfig_path, "a") {|file| file.puts key = value}
                end
            end
        end
    end
end