1. podfile文件中指定source源为master：

​​source 'https://github.com/CocoaPods/Specs.git'​​

​​添加在最上面即可​​

target 'DemoApp' do
    source 'https://github.com/CocoaPods/Specs.git'
    pod 'Alamofire', '~> 4.7'
    pod 'PKHUD', '~> 5.0'
    pod 'Toaster'
    pod 'Qiniu', '~> 7.2'
end

2.执行​​pod repo remove trunk​​移除trunk源

3.pod install 耐心等待下就好