使用第三方库xcode报错Cannot synthesize weak property because the current deployment target does not support weak references

解决方法：

1、项目->TARGETS->IOS->Build Settings->Apple LLVM 9,1 - Language - Objective C->Weak References inManual Retain Release改为YES

2、如果不行，在podfile文件底下加入下面的代码，'8.0'是对应的部署目标（deployment target） 删除库重新pod

platform:'ios','8.0'
target 'ddd’ do
pod ‘ZHPdfReadLib’, :path => ‘../PdfRead’

##################加入代码##################
    post_install do |installer|
        installer.pods_project.targets.each do |target|
            target.build_configurations.each do |config|
                config.build_settings['IPHONEOS_DEPLOYMENT_TARGET'] ='8.0'
            end
        end
    end
##################加入代码##################


end