如何使用Mapbox实现逐向导航

Question

我已经使用cocoapods安装了Mapbox。框架也附在我的项目上。但是，在我的viewController中，我无法导入MapboxDirections和MapboxNavigation。我只能导入Mapbox。为什么会这样？

podfile内容为：

# Uncomment the next line to define a global platform for your project
platform :ios, '11.1'

target 'TurnbyTurnMapBox' do
  # Comment the next line if you're not using Swift and don't want to use dynamic frameworks
  use_frameworks!

  # Pods for TurnbyTurnMapBox
pod 'MapboxNavigation', '~> 0.9'

end