In iOS, to detect faces in a picture, you can use either CIDetector (Apple) or Mobile Vision (Google)

In my point of view, Google Mobile Vision provide better performance.

Getting GoogleMobileVision with CocoaPods

# platform :ios, ’10.0’
use_frameworks!

target 'GoogleFaceDetection' do
  pod 'GoogleMobileVision/FaceDetector'
end

In Terminal, get to the project directory and run pod install

In this project, there are two modes.