原因工程中没有设置SWIFT_VERSION，为空，而依赖的第三方库使用了swift，若用公司网络下载pods下载不下来，建议采用电脑直接连接手机wifi网络（你的手机流量够用的情况下）。
解决方案：设置Targets->Build Settings->Combined(All)->User-Defined->SWIFT_VERSION，设置为4.0等。若没有SWIFT_VERSION属性就要在User-Defined下面点“+”添加，设置版本号。
-> Installing Zip (1.1.0) > Git download > Git download $ /usr/bin/git clone https://github.com/marmelroy/Zip.git /var/folders/4y/m9ckznh17111xdfwvn7xg0w40000gn/T/d20190611-5196-5q9vsg --template= --single-branch --depth 1 --branch 1.1.0 Cloning into '/var/folders/4y/m9ckznh17111xdfwvn7xg0w40000gn/T/d20190611-5196-5q9vsg'... Note: checking out 'e0935dcb2c99f4511ecf95cab5dcec0f25335829'. You are in 'detached HEAD' state. You can look around, make experimental changes and commit them, and you can discard any commits you make in this state without impacting any branches by performing another checkout. If you want to create a new branch to retain commits you create, you may do so (now or later) by using -b with the checkout command again. Example: git checkout -b <new-branch-name> > Copying Zip from `/Users/jiaguoshang/Library/Caches/CocoaPods/Pods/Release/Zip/1.1.0-8877e` to `Pods/Zip` -> Installing iOSDFULibrary (4.2.2) > Git download > Git download $ /usr/bin/git clone https://github.com/NordicSemiconductor/IOS-Pods-DFU-Library.git /var/folders/4y/m9ckznh17111xdfwvn7xg0w40000gn/T/d20190611-5196-1xw1fjc --template= --single-branch --depth 1 --branch 4.2.2 Cloning into '/var/folders/4y/m9ckznh17111xdfwvn7xg0w40000gn/T/d20190611-5196-1xw1fjc'... Note: checking out '422caf59d89f1ded7e9f403f17a5ea863b6b40ff'. You are in 'detached HEAD' state. You can look around, make experimental changes and commit them, and you can discard any commits you make in this state without impacting any branches by performing another checkout. If you want to create a new branch to retain commits you create, you may do so (now or later) by using -b with the checkout command again. Example: git checkout -b <new-branch-name> > Copying iOSDFULibrary from `/Users/jiaguoshang/Library/Caches/CocoaPods/Pods/Release/iOSDFULibrary/4.2.2-65a30` to `Pods/iOSDFULibrary` - Running pre install hooks [!] Unable to determine Swift version for the following pods: - `Zip` does not specify a Swift version and none of the targets (`ELock_Example`) integrating it have the `SWIFT_VERSION` attribute set. Please contact the author or set the `SWIFT_VERSION` attribute in at least one of the targets that integrate this pod.
