“Use Legacy Swift Language Version” (SWIFT_VERSION) is required to be configured correctly for targets which use Swift. Use the [Edit > Convert > To Current Swift Syntax…] menu to choose a Swift version or use the Build Settings editor to configure the build setting directly.
看到了几篇都找不到解决方法，最后在国外的网站上看到了一个解决方法是：
在Podfile上添加:
post_install do |installer|
installer.pods_project.targets.each do |target|
target.build_configurations.each do |config|
config.build_settings['SWIFT_VERSION'] = '3.0'
end
end
end
然后就pod update 下就可以编译了。
国内的解决方案：http://blog.csdn.net/u012847940/article/details/52229485（按照个人的情况来选择。）
