CocoaPods - 源码篇

前言

由于项目里业务线很多，集成了很多第三方pod库 和 私有pod库，整个pod project体积非常大。默认的Xcode 编译行为寻找依赖的project进行编译，并且是并行的。



我们做了如下改动，加快主工程编译速度：

.去除了主工程对 Pods target的依赖编译
.取消上面两个勾选
.在 Manage Scheme 里勾选了Pods project，以便于可以手动选择 Pods project进行编译

如果对Pods库更改了，我们可以手动选择 Pods Scheme 进行编译，然后再编译主工程，这样避免Pods不必要编译。

问题

每次pod install之后，pods scheme 自动消失了，我们找到 xcschememanagement.plist文件

cd demo/Pods/Pods.xcodeproj/xcuserdata/Green.xcuserdatad/xcschemes
cat xcschememanagement.plist

# 输出
<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE plist PUBLIC "-//Apple//DTD PLIST 1.0//EN" "http://www.apple.com/DTDs/PropertyList-1.0.dtd">
<plist version="1.0">
<dict>
<key>SchemeUserState</key>
<dict>
    <key>Pods.xcscheme</key>
    <dict>
        <key>isShown</key>
        <false/>
    </dict>
...

可以看到：Pods.xcscheme isShown 是 false，这样导致scheme 中没有Pods。

Pod Install 剖析

我们来看看 CocoaPods 源码

cd /Library/Ruby/Gems/2.0.0/gems/
#这里有很多版本，我们只看0.38.2

当我们执行 pod install，其实调用到Installer对象，

#文件位置：`cocoapods-0.38.2/lib/cocoapods/command/project.rb`

#初始化 Installer 对象       
def run_install_with_update(update)
    installer = Installer.new(config.sandbox, config.podfile, config.lockfile)
    installer.update = update

    #install 方法
    installer.install!
  end
end

install!

#文件位置：`cocoapods-0.38.2/lib/cocoapods/installer.rb`文件，

  #install 方法
def install!
  prepare
  resolve_dependencies

  #下载依赖
  download_dependencies
  determine_dependency_product_types
  verify_no_duplicate_framework_names
  verify_no_static_framework_transitive_dependencies
  verify_framework_usage

  #合成 pods project
  generate_pods_project

  integrate_user_project if config.integrate_targets?
  perform_post_install_actions
end

download_dependencies

#下载pods 资源
def download_dependencies
  UI.section 'Downloading dependencies' do
    create_file_accessors
    install_pod_sources
    run_podfile_pre_install_hooks
    clean_pod_sources
  end
end

generate_pods_project

#合成 pods project
def generate_pods_project
  UI.section 'Generating Pods project' do
    prepare_pods_project
    install_file_references
    install_libraries
    set_target_dependencies

    #执行Podfile 的post_install 代码块
    run_podfile_post_install_hooks

    #重新写入pod project，就是在这里修改了所有`pod.xcscheme` 的`isShown`为false
    write_pod_project

    share_development_pod_schemes
    write_lockfiles
  end
end

run post_install

#执行Podfile 的post_install 代码块
def run_podfile_post_install_hooks
  UI.message '- Running post install hooks' do
    executed = run_podfile_post_install_hook
    UI.message '- Podfile' if executed
  end
end


def run_podfile_post_install_hook
    #执行 post_install，这个代码块（block）可以在Podfile里指定
  podfile.post_install!(self)
rescue => e
  raise Informative, 'An error occurred while processing the post-install ' \
    'hook of the Podfile.' \
    "\n\n#{e.message}\n\n#{e.backtrace * "\n"}"
end

post_install

我们经常在 Podfile 里设置 @post_install 代码块:

#文件位置：`cocoapods-core-0.38.2/lib/cocoapods-core/podfile/dsl.rb` 文件

  def post_install(&block)
    @post_install_callback = block
  end    

write_pod_project

# 重新写入pod project，就是在这里修改了所有`pod.xcscheme` 的`isShown`为false
def write_pod_project
  UI.message "- Writing Xcode project file to #{UI.path sandbox.project_path}" do
    pods_project.pods.remove_from_project if pods_project.pods.empty?
    pods_project.development_pods.remove_from_project if pods_project.development_pods.empty?
    pods_project.sort(:groups_position => :below)

    ##重新创建schemes 文件，这里更改了isShown
    pods_project.recreate_user_schemes(false)
    pods_project.predictabilize_uuids if config.deterministic_uuids?
    pods_project.save
  end
end  

recreate_user_schemes

  #重新创建schemes 文件
def recreate_user_schemes(visible = true)
  schemes_dir = XCScheme.user_data_dir(path)
  FileUtils.rm_rf(schemes_dir)
  FileUtils.mkdir_p(schemes_dir)
  xcschememanagement = {}
  xcschememanagement['SchemeUserState'] = {}
  xcschememanagement['SuppressBuildableAutocreation'] = {}

  targets.each do |target|
    scheme = XCScheme.new
    scheme.add_build_target(target)
    scheme.save_as(path, target.name, false)
    xcschememanagement['SchemeUserState']["#{target.name}.xcscheme"] = {}

    #就是在这里修改的。
    xcschememanagement['SchemeUserState']["#{target.name}.xcscheme"]['isShown'] = visible
  end

  xcschememanagement_path = schemes_dir + 'xcschememanagement.plist'
  Xcodeproj.write_plist(xcschememanagement, xcschememanagement_path)
end

这样我们找到了根本问题，其实还是底层做了限制，每次 pod install 会重新生成 scheme 文件，并且每个 pod target 的 isShown 都是 false 。

Podfile 剖析

Podfile 其实是个 Ruby 类，对应 Cocoapods 的 Podfile class，我们可以看看Podfile class源码:

# 文件位置：/Library/Ruby/Gems/2.0.0/gems/cocoapods-core-0.38.2/lib/cocoapods-core/podfile/dsl.rb

module Pod 
 class Podfile
 module DSL
 ...

platform

指定 Pods target 的 platform

# @!group Target configuration
#   These settings are used to control the  CocoaPods generated project.
#
#   This starts out simply with stating what `platform` you are working  on. `xcodeproj` allows you to state specifically which project to link with.

# Specifies the platform for which a static library should be built.
#
# CocoaPods provides a default deployment target if one is not specified.
# The current default values are `4.3` for iOS, `10.6` for OS X and `2.0` for watchOS.
#
# If the deployment target requires it (iOS < `4.3`), `armv6` architecture will be added to `ARCHS`.
#
# @param    [Symbol] name
#           the name of platform, can be either `:osx` for OS X, `:ios`
#           for iOS or `:watchos` for watchOS.
#
# @param    [String, Version] target
#           The optional deployment.  If not provided a default value
#           according to the platform name will be assigned.
#
# @example  Specifying the platform
#
#           platform :ios, "4.0"
#           platform :ios
#
# @return   [void]

def platform(name, target = nil)
  # Support for deprecated options parameter
  target = target[:deployment_target] if target.is_a?(Hash)
  current_target_definition.set_platform(name, target)
end

xcodeproj

指定 Pods libraries 可以被哪个 project 链接。

# @Specifies the Xcode project that contains the target that the Pods library should be linked with.
# 
# @param    [String] path
#           the path of the project to link with
#
# @param    [Hash{String => symbol}] build_configurations
#           a hash where the keys are the name of the build
#           configurations in your Xcode project and the values are
#           Symbols that specify if the configuration should be based on
#           the `:debug` or `:release` configuration. If no explicit
#           mapping is specified for a configuration in your project, it
#           will default to `:release`.
#
# @example  Specifying the user project
#
#           # Look for target to link with in an Xcode project called
#           # `MyProject.xcodeproj`.
#           xcodeproj 'MyProject'
#
#           target :test do
#             # This Pods library links with a target in another project.
#             xcodeproj 'TestProject'
#           end
#
# @example  Using custom build configurations
#
#           xcodeproj 'TestProject', 'Mac App Store' => :release, 'Test' => :debug
#
#
# @return   [void]


def xcodeproj(path, build_configurations = {})
  current_target_definition.user_project_path = path
  current_target_definition.build_configurations = build_configurations
end

inhibit_all_warnings

指定 是否需要忽略警告

# @Inhibits **all** the warnings from the CocoaPods libraries.
#
#
# This attribute is inherited by child target definitions.
#
# If you would like to inhibit warnings per Pod you can use the following syntax:
#
#     pod 'SSZipArchive', :inhibit_warnings => true

def inhibit_all_warnings!
  current_target_definition.inhibit_all_warnings = true
end

use_frameworks

指定是否使用 framework

# @Use frameworks instead of static libraries for Pods.
#
# ------
#
# This attribute is inherited by child target definitions.
#    

def use_frameworks!(flag = true)
  current_target_definition.use_frameworks!(flag)
end

workspace

指定 合成的 workspace 路径

# @!group Workspace
#
#   This group list the options to configure workspace and to set global settings.
# Specifies the Xcode workspace that should contain all the projects.
#
# -----
#
# If no explicit Xcode workspace is specified and only **one** project
# exists in the same directory as the Podfile, then the name of that project is used as the workspace’s name.
#
# @param    [String] path
#           path of the workspace.
#
# @example  Specifying a workspace
#
#           workspace 'MyWorkspace'
#
# @return   [void]


def workspace(path)
  set_hash_value('workspace', path.to_s)
end

source

指定 specs 仓库源

# @!group Sources
#
#   The Podfile retrieves specs from a given list of sources (repositories).
#
#   Sources are __global__ and they are not stored per target definition.
# Specifies the location of specs
#
# -----
#
# Use this method to specify sources. The order of the sources is
# relevant. CocoaPods will use the highest version of a Pod of the first
# source which includes the Pod (regardless whether other sources have a
# higher version).
#
# @param    [String] source
#           The URL of a specs repository.
#
# @example  Specifying to first use the Artsy repository and then the
#           CocoaPods Master Repository
#
#           source 'https://github.com/artsy/Specs.git'
#           source 'https://github.com/CocoaPods/Specs.git'
#
# @return   [void]

def source(source)
  hash_sources = get_hash_value('sources') || []
  hash_sources << source
  set_hash_value('sources', hash_sources.uniq)
end

post_install

设置 installer 之后的执行的代码块

# This hook allows you to make any last changes to the generated Xcode
# project before it is written to disk, or any other tasks you might want to perform.
#
# It receives the [`Pod::Installer`](http://rubydoc.info/gems/cocoapods/Pod/Installer/) as its only argument.
#
# @example  Customising the build settings of all targets
#
#   post_install do |installer|
#     installer.pods_project.targets.each do |target|
#       target.build_configurations.each do |config|
#         config.build_settings['GCC_ENABLE_OBJC_GC'] = 'supported'
#       end
#     end
#   end
#
# @return   [void]
#

def post_install(&block)
  @post_install_callback = block
end

Podfile 自定义

我们在Podfile中增加如下代码：

#设置 Podfile 对象 @post_install_callback 成员
self.post_install do |installer|
$KDPod_Project
begin
    $KDPod_Project=installer.project
    rescue
    puts "installer.project is delete"
    $KDPod_Project=installer.pods_project
end
installer.use_default_plugins = false
$KDPod_Project.targets.each do |target|
    #设置ORGANIZATIONNAME 、 CLASSPREFIX
    #target.project.root_object.attributes['ORGANIZATIONNAME']='xxxxx.xxx'
    #target.project.root_object.attributes['CLASSPREFIX']='xxxx'
    target.build_configurations.each do |config|

        #设置target的编译后生成目录
        config.build_settings['CONFIGURATION_TEMP_DIR'] = './build'
        config.build_settings['ONLY_ACTIVE_ARCH'] = 'NO'
    end
end

# 延迟执行
def kdperformSelector(time)
    before=Time.now
    fork do
        sleep(1) until Time.now-before >= time
        yield
    end
end


#延迟3秒 更改pods scheme visabled
kdperformSelector(3){
    ##update pod visabled
    $schemes_dir = Xcodeproj::XCScheme.user_data_dir($KDPod_Project.path)
    $xcschememanagement_path = $schemes_dir + 'xcschememanagement.plist'
    $xcschememanagement_content = Xcodeproj.read_plist($xcschememanagement_path)

    #设置 isShown 属性
    $xcschememanagement_content['SchemeUserState']["Pods.xcscheme"]['isShown'] = true
    FileUtils.rm_rf($xcschememanagement_path)
    Xcodeproj.write_plist($xcschememanagement_content,$xcschememanagement_path)
    #    puts $xcschememanagement_content
    #    $KDPod_Project.recreate_user_schemes(true)
    $KDPod_Project.save
    puts "KDPod_Project.save"
}
end

我们新for一个进程，在 download_dependencies 之后 延迟了3秒执行更新 pods.xschemeisShown 属性。
这样就可以显示Pods Scheme了。

这里只是做个例子，重要的是，了解了源码，我们就可以对project进行其他配置。