蘋果每年都更新 Swift 版本，但是平常項(xiàng)目中使用的一些開源庫卻不能及時(shí)更新，使用那就需要一部分庫繼續(xù)使用 Swift3.2 版本，一部分使用 Swift4，那么在 Podfile 中應(yīng)該這么寫

platform :ios, '9.0'

target 'gate' do
   use_frameworks!
   pod 'RxSwift',    '~> 4.0'
   pod 'RxCocoa',    '~> 4.0'
   pod 'WBAlamofire'
   pod 'HandyJSON'
   pod 'Kingfisher', '~> 4.8.0'
   pod 'SnapKit'
   pod 'MJRefresh', '~> 3.1.15.3'
   pod 'JPush'
   pod 'IQKeyboardManagerSwift', '~> 6.0.4'
   pod 'SDWebImage', '~> 4.0'
   pod 'CHKLineChartKit'
   
   pod 'MZFormSheetPresentationController'
   pod 'SwiftyJSON'

end
post_install do |installer|
   installer.pods_project.targets.each do |target|
       if ['CHKLineChartKit','Kingfisher','MZFormSheetPresentationController','SwiftyJSON'].include? target.name
           target.build_configurations.each do |config|
               config.build_settings['SWIFT_VERSION'] = '4.0'
               config.build_settings['ONLY_ACTIVE_ARCH'] = 'NO'
           end
           else
           target.build_configurations.each do |config|
               config.build_settings['SWIFT_VERSION'] = '4.2'
               config.build_settings['ONLY_ACTIVE_ARCH'] = 'NO'
           end
       end
   end
end