demo can read freq which come from mic of around where ，study ios program。

DetectingAudioFrequency-master
..............................\.gitignore
..............................\DetectingSoundFrequency.xcodeproj
..............................\.................................\project.pbxproj
..............................\.................................\xcuserdata
..............................\.................................\..........\mac.xcuserdatad
..............................\.................................\..........\...............\xcschemes
..............................\.................................\..........\...............\.........\DetectingSoundFrequency.xcscheme
..............................\.................................\..........\...............\.........\xcschememanagement.plist
..............................\DetectingSoundFrequency
..............................\.......................\AppDelegate.h
..............................\.......................\AppDelegate.mm
..............................\.......................\Base.lproj
..............................\.......................\..........\Main.storyboard
..............................\.......................\DetectingSoundFrequency-Info.plist
..............................\.......................\DetectingSoundFrequency-Prefix.pch
..............................\.......................\FFTHelper.h
..............................\.......................\FFTHelper.mm
..............................\.......................\Images.xcassets
..............................\.......................\...............\AppIcon.appiconset
..............................\.......................\...............\..................\Contents.json
..............................\.......................\...............\LaunchImage.launchimage
..............................\.......................\...............\.......................\Contents.json
..............................\.......................\ViewController.h
..............................\.......................\ViewController.mm
..............................\.......................\en.lproj
..............................\.......................\........\InfoPlist.strings
..............................\.......................\main.mm
..............................\.......................\mo_audio.h
..............................\.......................\mo_audio.mm
..............................\.......................\mo_def.h
..............................\.......................\mo_gfx.h
..............................\.......................\mo_gfx.mm
..............................\DetectingSoundFrequencyTests
..............................\............................\DetectingSoundFrequencyTests-Info.plist
..............................\............................\DetectingSoundFrequencyTests.m
..............................\............................\en.lproj
..............................\............................\........\InfoPlist.strings
..............................\README.md

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