是什么让“FBAudienceNetwork”链接耗时 20 秒？

Question

Recently I found out that the reason of taking ~20secs to link the project is because of "FBAudienceNetwork" SDK install by CocoaPods, as this image shows:

You can clone the demo project here:

git@github.com:JohnnyTseng/FBDemoProject.git

This is a clean project that only contains "FBAudienceNetwork" installed by CocoaPods, and it'll take ~20secs to link the project.

Steps to reproduce:

1. Install "FBAudienceNetwork" using CocoaPods
2. Build the app
3. The linking time will take ~ 20secs (on MBPR 16", 16G, 8 Core)

The interesting thing is, if you install even 10+ libraries with CocoaPods, the linking time is still very fast, once you installed "FBAudienceNetwork", it took ~20secs for each incremental build.

Does anyone know how this happens? I'm very curious but have not enough knowledge to dig into this issue

Thank you!

Answer 1

I have this problem too for quite some time and it is very annoying. I don't know a way to fix the linking time issue (maybe use the dynamic version of the framework, not static, but this means managing this dependency manually, which is a no-go for me), I think it is up to the FB team to fix.

But there is a workaround - avoid linking FBAudienceNetwork at all.

This reduces the issue to only the development related to FB ads, which is luckily not that often.

• create a separate target in XCode and Podfile
• don't specify FBAudienceNetwork dependency in Podfile
• create preprocessor macros to exclude FBAudienceNetwork related code from compilation
• create a helper class that will encapsulate all FB related logic
• use factory method with dummy ad helper

Some details:

• target

Suppose your fb-free target is FBDemoProject-no-fb . Then in Podfile :

target 'FBDemoProject' do
  # Comment the next line if you don't want to use dynamic frameworks
  use_frameworks!

  # Pods for FBDemoProject
  pod 'FBAudienceNetwork'
  # any other libs

end

target 'FBDemoProject-no-fb' do
  # Comment the next line if you don't want to use dynamic frameworks
  use_frameworks!

  # any other libs

end

• preprocessors:

for usage in swift: Other swift flags -> -D NO_FB_AD

for usage in obj-c or header files: Preprocessor macros -> NO_FB_AD=1

• helpers:

protocol FbAd {
    func tryLoad()
    func isLoaded() -> Bool
    func tryShow(_ from: UIViewController?)
}

class FbAdFactory {
    static func create(
        _ placementId: String,
        _ didLoad: @escaping () -> (), //to be used in `FBInterstitialAdDelegate` methods - just to get an idea
        _ didClose: @escaping () -> (),
        _ onError: @escaping () -> ()
    ) -> NvFbAd {
        #if !NO_FB_AD
            return FbAdHelper(
                placementId,
                didLoad,
                didClose,
                onError)
        #else
            return FbAdDummy() //dummy implementation
        #endif
    }
}

Use conditional import in FbAdHelper :

//to avoid compiler errors
#if canImport(FBAudienceNetwork)
    import FBAudienceNetwork
#endif

#if !NO_FB_AD
class FbAdHelper: NSObject, FbAd, FBInterstitialAdDelegate {
    //here go encapsulated logic and delegate methods
}
#endif

• then in your controller:

var fbAdHelper: NvFbAd!

//...

self.fbAdHelper = FbAdFactory.create("placementId",
            { },
            { },
            { }
        )