About static framework used

About static framework used

准备一个空项目、两个framework 静态库和 .xcconfig 文件

• 目录结构

  .
  ├── AFNetworking
  │   ├── AFAutoPurgingImageCache.h
  │   ├── AFCompatibilityMacros.h
  │   ├── AFHTTPSessionManager.h
  │   ├── AFImageDownloader.h
  │   ├── AFNetworkActivityIndicatorManager.h
  │   ├── AFNetworkReachabilityManager.h
  │   ├── AFNetworking-umbrella.h
  │   ├── AFNetworking.h
  │   ├── AFSecurityPolicy.h
  │   ├── AFURLRequestSerialization.h
  │   ├── AFURLResponseSerialization.h
  │   ├── AFURLSessionManager.h
  │   ├── UIActivityIndicatorView+AFNetworking.h
  │   ├── UIButton+AFNetworking.h
  │   ├── UIImageView+AFNetworking.h
  │   ├── UIKit+AFNetworking.h
  │   ├── UIProgressView+AFNetworking.h
  │   ├── UIRefreshControl+AFNetworking.h
  │   ├── WKWebView+AFNetworking.h
  │   └── libAFNetworking.a
  ├── AFNetworking2
  │   ├── AFAutoPurgingImageCache.h
  │   ├── AFCompatibilityMacros.h
  │   ├── AFHTTPSessionManager.h
  │   ├── AFImageDownloader.h
  │   ├── AFNetworkActivityIndicatorManager.h
  │   ├── AFNetworkReachabilityManager.h
  │   ├── AFNetworking-umbrella.h
  │   ├── AFNetworking.h
  │   ├── AFSecurityPolicy.h
  │   ├── AFURLRequestSerialization.h
  │   ├── AFURLResponseSerialization.h
  │   ├── AFURLSessionManager.h
  │   ├── UIActivityIndicatorView+AFNetworking.h
  │   ├── UIButton+AFNetworking.h
  │   ├── UIImageView+AFNetworking.h
  │   ├── UIKit+AFNetworking.h
  │   ├── UIProgressView+AFNetworking.h
  │   ├── UIRefreshControl+AFNetworking.h
  │   ├── WKWebView+AFNetworking.h
  │   └── libAFNetworking2.a
  ├── StaticFrameworkUsed
  │   ├── AppDelegate.swift
  │   ├── Assets.xcassets
  │   ├── Base.lproj
  │   │   ├── LaunchScreen.storyboard
  │   │   └── Main.storyboard
  │   ├── Config.xcconfig
  │   ├── Info.plist
  │   ├── SceneDelegate.swift
  │   └── ViewController.swift
  └── StaticFrameworkUsed.xcodeproj

这里面两套 AFN 的代码完全相同，只是最终链接生成的静态库名称不同
项目中没有 import和使用 AFN

• .xcconfig 配置

  // 1. -I: 头文件
  HEADER_SEARCH_PATHS = $(inherited) "${SRCROOT}/AFNetworking" "${SRCROOT}/AFNetworking2"
  // 2. -L: library 所在目录
  LIBRARY_SEARCH_PATHS = $(inherited) "${SRCROOT}/AFNetworking" "${SRCROOT}/AFNetworking2"
  // 3. -l 名称
  OTHER_LDFLAGS = $(inherited) -l "AFNetworking" -l "AFNetworking2"

此时编译、运行都正常

由于链接一个静态库时默认采用的是 noall_load，所以链接的时候已经找到了 AFNetworking，后面再去找 AFNetworking2的时候就会被剥离

• 将其改成 all_load 或 -ObjC

  OTHER_LDFLAGS = $(inherited) -all_load -l "AFNetworking" -l "AFNetworking2"
  

• 再次编译，提示符号冲突

  
  ...省略
  
  duplicate symbol '_OBJC_IVAR_$_AFRefreshControlNotificationObserver._refreshControl' in:
      /Users/shenyj/Desktop/StaticFrameworkUsed/AFNetworking/libAFNetworking.a(UIRefreshControl+AFNetworking.o)
      /Users/shenyj/Desktop/StaticFrameworkUsed/AFNetworking2/libAFNetworking2.a(UIRefreshControl+AFNetworking.o)
  ld: 223 duplicate symbols for architecture x86_64
  clang: error: linker command failed with exit code 1 (use -v to see invocation)
  
  

使用force_load与load_hidden解决符号冲突

• load_hidden 的介绍

  -load_hidden path_to_archive
      Uses specified static library as usual, but treats all global symbols from the static library to as if they are
      visibility hidden.  Useful when building a dynamic library that uses a static library but does not want to export
      anything from that static library.

  man ld -> 搜索关键字即可

  将隐藏所有的全局符号，相当于设置为本地符号，这样将其隐藏，也就不会产生符号冲突了

• 使用 force_load 与 load_hidden, 修改 .xcconfig 如下

  // 1. -I: 头文件
  HEADER_SEARCH_PATHS = $(inherited) "${SRCROOT}/AFNetworking" "${SRCROOT}/AFNetworking2"
  // 2. -L: library 所在目录
  LIBRARY_SEARCH_PATHS = $(inherited) "${SRCROOT}/AFNetworking" "${SRCROOT}/AFNetworking2"
  // 3. -l 名称
  //OTHER_LDFLAGS = $(inherited) -all_load -l "AFNetworking" -l "AFNetworking2"
  OTHER_LDFLAGS = $(inherited) -l "AFNetworking" -l "AFNetworking2" -Xlinker -force_load -Xlinker "${SRCROOT}/AFNetworking/libAFNetworking.a" -Xlinker -load_hidden -Xlinker "${SRCROOT}/AFNetworking2/libAFNetworking2.a"
  

这样也能解决符号冲突的问题

示例项目 下载链接