I had the same problem as Michal said that the installation problem, if you use cocoapods , go to your files/pods/Alamofires/Source project and make sure that you have 9 files exactly like this image, and make sure that the MultipartFormData.swift file is

if you are not using cocoapods , just open the Alamofire folder and go to the source folder and make sure you have the same files.
if you did not find MultipartFormData.swift , it means that your version of Alamofire does not support MultipartFormData, then you will need to get the latest version here of Alamofire , or if you use cocoapods , you need to update the Alamofire pod line on the podfile to look like
platform :ios, '8.0' use_frameworks! target 'ProjectName' do pod 'Alamofire', :git => 'https://github.com/Alamofire/Alamofire.git', :branch => 'master' end target 'ProjectNameTests' do end
after updating your pod file you need to run this command to update the cocoapods project
pod install
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