find /Applications/Xcode6-Beta.app/Contents/ -name "*swift*"
可以找到swift相关的文件，简单过滤后，如下的文件比较重要：
/Applications/Xcode6-Beta.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/swift
/Applications/Xcode6-Beta.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/swift-demangle
/Applications/Xcode6-Beta.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/swift-ide-test
/Applications/Xcode6-Beta.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/swift-stdlib-tool
/Applications/Xcode6-Beta.app/Contents/SharedFrameworks/LLDB.framework/Versions/A/Resources/repl_swift
/Applications/Xcode6-Beta.app/Contents//Developer/Toolchains/XcodeDefault.xctoolchain/usr/share/man/man1/swift.1
从找到的文件中我们可以看到包含 man 手册文件，我们首先看看手册的内容：
swift(1) Swift Documentation swift(1)
NAME
swift - <strong>the amazingly new programming language</strong>
SYNOPSIS
swift [-emit-object|-emit-assembly|-emit-library|-i]
[-help]
-o output-file
input-filenames
The full list of supported options is available via "swift -help".
DESCRIPTION
Swift is a new, high performance systems programming language. It has a clean and modern syntax,
and offers seamless access to existing C and Objective-C code and frameworks, and is memory safe
(by default).
Although inspired by Objective-C and many other languages, Swift is not itself a C-derived
language. As a complete and independent language, Swift packages core features like flow control,
data structures, and functions, with high-level constructs like objects, protocols, closures, and
generics. Swift embraces modules, eliminating the need for headers and the code duplication they
entail.
2014-05-17 swift(1)
从手册中可以得到的信息也非常有限，但是看到参数：-help，我们看看帮助会输出什么：
OVERVIEW: Swift compiler
USAGE: swift [options] <inputs>
MODES:
-dump-ast Parse and type-check input file(s) and dump AST(s)
-dump-parse Parse input file(s) and dump AST(s)
-emit-assembly Emit assembly file(s) (-S)
-emit-bc Emit LLVM BC file(s)
-emit-executable Emit a linked executable
-emit-ir Emit LLVM IR file(s)
-emit-library Emit a linked library
-emit-object Emit object file(s) (-c)
-emit-silgen Emit raw SIL file(s)
-emit-sil Emit canonical SIL file(s)
-integrated-repl Integrated REPL mode
-i Immediate mode
-lldb-repl LLDB-enhanced REPL mode
-parse Parse input file(s)
-print-ast Parse and type-check input file(s) and pretty print AST(s)
-repl REPL mode
OPTIONS:
-application-extension Restrict code to those available for App Extensions
-arch <arch> Compile for architecture <arch>
-assert-config <value> Specify the assert_configuration replacement. Possible values are Debug, Release, Replacement.
-D <value> Specifies one or more build configuration options
-emit-dependencies Emit Make-compatible dependencies files
-emit-module-path <path>
Emit an importable module to <path>
-emit-module Emit an importable module
-emit-objc-header-path <path>
Emit an Objective-C header file to <path>
-emit-objc-header Emit an Objective-C header file
-framework <value> Specifies a framework which should be linked against
-F <value> Add directory to framework search path
-g Emit debug info
-help Display available options
-import-underlying-module
Implicitly imports the Objective-C half of a module
-I <value> Add directory to the import search path
-j <n> Number of commands to execute in parallel
-L <value> Add directory to library link search path
-l<value> Specifies a library which should be linked against
-module-cache-path <value>
Specifies the Clang module cache path
-module-link-name <value>
Library to link against when using this module
-module-name <value> Name of the module to build
-nostdimport Don't search the standard library import path for modules
-output-file-map <path> A file which specifies the location of outputs
-o <file> Write output to <file>
-parse-as-library Parse the input file(s) as libraries, not scripts
-parse-sil Parse the input file as SIL code, not Swift source
-save-temps Save intermediate compilation results
-sdk <sdk> Compile against <sdk>
-serialize-diagnostics Serialize diagnostics in a binary format
-target-cpu <value> Generate code for a particular CPU variant
-target-feature [+-]<feature-name>
Generate code with a particular CPU feature enabled or disabled
-target <value> Generate code for the given target
-version Print version information and exit
-v Show commands to run and use verbose output
-Xcc <arg> Pass <arg> to the C/C++/Objective-C compiler
-Xfrontend <arg> Pass <arg> to the Swift frontend
-Xlinker <value> Specifies an option which should be passed to the linker
-Xllvm <arg> Pass <arg> to LLVM.
这么多参数到底怎么用呢？！我们一起来看看 xcode 是怎么使用的。
打开xcode6新建一个空工程，取名“FuckSwift”：
将工程的Deployment Target改成 5.0，然后编译，并在设备上运行。我手上的设备是iPad2-iOS7.0.4，可以正常运行。为什么可以正常运行？swift相关的运行时库怎么处理？我们打开编译好的app目录：
可以看到比以前的程序多了一个目录 Frameworks，内容如下：
因此，在iOS8之下的设备上，程序打包的时候带上了必要的运行库。对于iOS8，目前还没法解开 dyld cache 也就无法知道设备上是否带了这些库，不过应该会带。
接上文，我们建立测试工程的目的是为了看看 xcode 如何使用 swift 编译工具，xcoce编译时的相关参数如下：
/Applications/Xcode6-Beta.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/swift
-target armv7-apple-ios5.0
-module-name FuckSwift
-O0
-sdk /Applications/Xcode6-Beta.app/Contents/Developer/Platforms/iPhoneOS.platform/Developer/SDKs/iPhoneOS8.0.sdk
-g
-module-cache-path /Users/proteas/Library/Developer/Xcode/DerivedData/ModuleCache
-I /Users/proteas/Library/Developer/Xcode/DerivedData/FuckSwift-czflmbyelvdrnvaxblvpkcrhfbie/Build/Products/Debug-iphoneos
-F /Users/proteas/Library/Developer/Xcode/DerivedData/FuckSwift-czflmbyelvdrnvaxblvpkcrhfbie/Build/Products/Debug-iphoneos
-parse-as-library
-c
-j8
/Users/proteas/Desktop/FuckSwift/FuckSwift/AppDelegate.swift
-output-file-map /Users/proteas/Library/Developer/Xcode/DerivedData/FuckSwift-czflmbyelvdrnvaxblvpkcrhfbie/Build/Intermediates/FuckSwift.build/Debug-iphoneos/FuckSwift.build/Objects-normal/armv7/FuckSwift-OutputFileMap.json
-serialize-diagnostics
-emit-dependencies
-emit-module
-emit-module-path /Users/proteas/Library/Developer/Xcode/DerivedData/FuckSwift-czflmbyelvdrnvaxblvpkcrhfbie/Build/Intermediates/FuckSwift.build/Debug-iphoneos/FuckSwift.build/Objects-normal/armv7/FuckSwift.swiftmodule
-Xcc
-iquote
-Xcc /Users/proteas/Library/Developer/Xcode/DerivedData/FuckSwift-czflmbyelvdrnvaxblvpkcrhfbie/Build/Intermediates/FuckSwift.build/Debug-iphoneos/FuckSwift.build/FuckSwift-generated-files.hmap
-Xcc -I/Users/proteas/Library/Developer/Xcode/DerivedData/FuckSwift-czflmbyelvdrnvaxblvpkcrhfbie/Build/Intermediates/FuckSwift.build/Debug-iphoneos/FuckSwift.build/FuckSwift-own-target-headers.hmap
-Xcc -I/Users/proteas/Library/Developer/Xcode/DerivedData/FuckSwift-czflmbyelvdrnvaxblvpkcrhfbie/Build/Intermediates/FuckSwift.build/Debug-iphoneos/FuckSwift.build/FuckSwift-all-target-headers.hmap
-Xcc
-iquote
-Xcc /Users/proteas/Library/Developer/Xcode/DerivedData/FuckSwift-czflmbyelvdrnvaxblvpkcrhfbie/Build/Intermediates/FuckSwift.build/Debug-iphoneos/FuckSwift.build/FuckSwift-project-headers.hmap -Xcc -I/Users/proteas/Library/Developer/Xcode/DerivedData/FuckSwift-czflmbyelvdrnvaxblvpkcrhfbie/Build/Products/Debug-iphoneos/include
-Xcc
-I/Applications/Xcode6-Beta.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/include
-Xcc -I/Users/proteas/Library/Developer/Xcode/DerivedData/FuckSwift-czflmbyelvdrnvaxblvpkcrhfbie/Build/Intermediates/FuckSwift.build/Debug-iphoneos/FuckSwift.build/DerivedSources/armv7
-Xcc -I/Users/proteas/Library/Developer/Xcode/DerivedData/FuckSwift-czflmbyelvdrnvaxblvpkcrhfbie/Build/Intermediates/FuckSwift.build/Debug-iphoneos/FuckSwift.build/DerivedSources
-Xcc
-DDEBUG=1
-emit-objc-header
-emit-objc-header-path /Users/proteas/Library/Developer/Xcode/DerivedData/FuckSwift-czflmbyelvdrnvaxblvpkcrhfbie/Build/Intermediates/FuckSwift.build/Debug-iphoneos/FuckSwift.build/Objects-normal/armv7/FuckSwift-Swift.h
参数还是太多，继续精简，把去掉绝对路径：
swift -target armv7-apple-ios5.0
-module-name FuckSwift
-O0
-sdk iPhoneOS8.0.sdk
-g
-module-cache-path ModuleCache
-I Debug-iphoneos
-F Debug-iphoneos
-parse-as-library
-c
-j8
AppDelegate.swift
-output-file-map FuckSwift-OutputFileMap.json
-serialize-diagnostics
-emit-dependencies
-emit-module
-emit-module-path FuckSwift.swiftmodule
-Xcc -iquote
-Xcc FuckSwift-generated-files.hmap
-Xcc -IFuckSwift-own-target-headers.hmap
-Xcc -IFuckSwift-all-target-headers.hmap
-Xcc -iquote
-Xcc FuckSwift-project-headers.hmap
-Xcc -Iinclude
-Xcc -I/usr/include
-Xcc -Iarmv7
-Xcc -IDerivedSources
-Xcc -DDEBUG=1
<strong>-emit-objc-header
-emit-objc-header-path FuckSwift-Swift.h</strong>
这样就相对清晰了。这里面的参数大家可以对照上述的帮助查看，这里我们一起看两点：
1、Xcc ：Pass to the C/C++/Objective-C compiler，这里我们可以得到：swift代码很可能最终被转变成C/C++/Objective-C代码进行静态编译。
2、会生成FuckSwift-Swift.h头文件，对比下这个文件与swift文件。
@UIApplicationMain
class AppDelegate: UIResponder, UIApplicationDelegate {
var window: UIWindow?
func application(application: UIApplication, didFinishLaunchingWithOptions launchOptions: NSDictionary?) -> Bool {
self.window = UIWindow(frame: UIScreen.mainScreen().bounds)
self.window!.backgroundColor = UIColor.whiteColor()
self.window!.makeKeyAndVisible()
return true
}
func applicationWillResignActive(application: UIApplication) {
}
func applicationDidEnterBackground(application: UIApplication) {
}
func applicationWillEnterForeground(application: UIApplication) {
}
func applicationDidBecomeActive(application: UIApplication) {
}
func applicationWillTerminate(application: UIApplication) {
}
}
SWIFT_CLASS("_TtC9FuckSwift11AppDelegate")
@interface AppDelegate : UIResponder <UIApplicationDelegate>
@property (nonatomic) UIWindow * window;
- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions;
- (void)applicationWillResignActive:(UIApplication *)application;
- (void)applicationDidEnterBackground:(UIApplication *)application;
- (void)applicationWillEnterForeground:(UIApplication *)application;
- (void)applicationDidBecomeActive:(UIApplication *)application;
- (void)applicationWillTerminate:(UIApplication *)application;
- (instancetype)init OBJC_DESIGNATED_INITIALIZER;
@end
可以看到swift程序是被转换了的，但是是不是转换成了Objective-C程序呢？还需要进一步分析。
打开IDA，加载测试程序的MachO：
我们重点看下函数窗口：
从函数名上我们可以得到如下结论：
1、可以看到函数名被“改编”了。
2、swift代码并不是被简单得编译成了ObjC代码
3、swift代码最终被编译成了纯C代码，相对于ObjC来说省去了运行时查表进行函数调用的开销，执行效率应该比ObjC要高。
4、从文档上看swfit相对于ObjC来说是更加动态的语言，开发效率也应该比ObjC高
5、对于越狱开发来说，我们只要像Hook C函数那样来Hook swift 函数就可以了，因此MobileSubstrate还是可以工作的。
6、生成的代码还是要遵循 ARM 的ABI标准
就像C++的名称改编一样，改编后的名称虽然可以手工还原但是太麻烦，最好找到工具来做这一件事。前文，我们在查找swift相关的文件时看到一个工具：swift-demangle，下面我们就用它来demangle改编后的名称，看看可以得到什么。
首先，我们切换命令行到xcode6的命令行工具：
sudo xcode-select --switch /Applications/Xcode6-Beta.app/Contents/Developer
然后，我们看看swift-demangle的命令行参数：
USAGE: swift-demangle [options] [mangled name...]
OPTIONS:
-compact - Compact mode (only emit the demangled names)
-expand - Expand mode (show node structure of the demangling)
-help - Display available options (-help-hidden for more)
-no-sugar - No sugar mode (disable common language idioms such as ? and [] from the output)
-tree-only - Tree-only mode (do not show the demangled string)
-version - Display the version of this program
从IDA中复制一个函数名，如：
__TToFC9FuckSwift11AppDelegate26applicationDidBecomeActivefS0_FCSo13UIApplicationT_
我们执行如下命令：
xcrun swift-demangle "__TToFC9FuckSwift11AppDelegate26applicationDidBecomeActivefS0_FCSo13UIApplicationT_"
得到输出：
_TToFC9FuckSwift11AppDelegate26applicationDidBecomeActivefS0_FCSo13UIApplicationT_ ---> @objc FuckSwift.AppDelegate.applicationDidBecomeActive (FuckSwift.AppDelegate)(ObjectiveC.UIApplication) -> ()
可以看到函数被还原。
到这里我们停下，看看swift对越狱开发的影响：
1、目前无法使用class-dump得到ObjC的头文件。
2、MobileSubstrate应该还可以正常工作。
3、可以使用demangle工具还原函数名，后期这部分工作IDA可能会自动支持。
总之，对越狱开发的流程会稍微有影响，针对应用的越狱开发还可以存在。
下面我们看看命令行工具swift-ide-test的参数：
OVERVIEW: Swift IDE Test
USAGE: swift-ide-test [options] [input files...]
OPTIONS:
-D=<string> - Build configurations
-F=<string> - add a directory to the framework search path
-I=<string> - add a directory to the import search path
-annotate-print - Annotate AST printing
-code-completion-diagnostics - Print compiler diagnostics while doing code completion
-code-completion-token=<string> - Code completion token name
-comments-xml-schema=<string> - Filename of the RelaxNG schema for documentation comments
-enable-objc-factory-method-constructors - Implicitly import Objective-C factory methods as initializers
-enable-objc-implicit-properties - Implicitly import Objective-C getter/setter pairs as properties
-explode-pattern-binding-decls - Separate pattern binding decls into individual var decls
-fatal-assembler-warnings - Consider warnings as error
-fully-qualified-types - Print fully qualified types
-fully-qualified-types-if-ambiguous - Print types fully-qualified if they would be ambiguous otherwise
-function-definitions - Print function bodies
-help - Display available options (-help-hidden for more)
-implicit-objc-with - Make the "with" implicit in initializers
-import-objc-header=<string> - header to implicitly import
-module-cache-path=<string> - Clang module cache path
-module-print-hidden - Print non-exported imported or submodules
-module-print-skip-overlay - Skip Swift overlay modules
-module-print-submodules - Recursively print submodules
-module-to-print=<string> - Name of the module to print
-objc-bridge-dictionary - Bridge Dictionary<K, V> to NSDictionary
-prefer-type-repr - When printing types, prefer printing TypeReprs
-print-after-all - Print IR after each pass
-print-before-all - Print IR before each pass
Mode:
-code-completion - Perform code completion
-repl-code-completion - Perform REPL-style code completion
-syntax-coloring - Perform syntax coloring
-structure - Perform document structure annotation
-annotate - Perform semantic annotation
-test-input-complete - Check if input source is complete
-print-ast-not-typechecked - Print the non-typechecked AST
-print-ast-typechecked - Print the typechecked AST
-print-module - Print visible declarations in a module
-print-types - Print types of all subexpressions and declarations in the AST
-print-comments - Print documentation comments attached to decls
-print-module-comments - Given a module, print documentation comments attached to decls
-print-module-imports - Recursively print all imports visible from a particular module
-print-usrs - Print USRs for all decls
-parse-rest - Parse a ReST file
-print-implicit-attrs - Print implicit attributes
-print-regular-comments - Print regular comments from clang module headers
-print-stats - Print statistics
-sdk=<string> - path to the SDK to build against
-skip-private-stdlib-decls - Don't print declarations that start with '_'
-skip-unavailable - Don't print unavailable declarations
-source-filename=<string> - Name of the source file
-split-objc-selectors - Split Objective-C selectors
-stats - Enable statistics output from program (available with Asserts)
-synthesize-sugar-on-types - Always print Array and Optional with sugar
-target=<string> - target triple
-terminal - Use terminal color for source annotations
-time-passes - Time each pass, printing elapsed time for each on exit
-typecheck - Type check the AST
-version - Display the version of this program
从参数上看，这很可能是xcode的内部工具，用来做代码完成与检查的。这里不具体分析，感兴趣的兄弟可以自己试试。
下面我们继续回到 swift 工具上，首先看看parse的输出，执行如下命令：
xcrun swift AppDelegate.swift -dump-parse
得到如下输出：
(source_file
(import_decl UIKit')
(class_decl "AppDelegate" type='<null type>' inherits: <null>, <null>
(pattern_binding_decl
(pattern_typed
(pattern_named 'window')
))
(var_decl "window" type='<null type>' storage_kind='stored')
(func_decl "application(_:didFinishLaunchingWithOptions:)" type='<null type>'
(body_params
(pattern_typed implicit
(pattern_named implicit 'self'))
(pattern_tuple
(pattern_typed
(pattern_named 'application')
(type_ident
(component id='UIApplication' bind=none)))
(pattern_typed
(pattern_named 'launchOptions')
)))
(result
(type_ident
(component id='Bool' bind=none)))
(brace_stmt
(sequence_expr type='<null>'
(unresolved_dot_expr type='<null>' field 'window'
(declref_expr type='<null>' decl=AppDelegate.(file).AppDelegate.func decl.self@AppDelegate.swift:17:10 specialized=yes))
(assign_expr
(**NULL EXPRESSION**)
(**NULL EXPRESSION**))
(call_expr type='<null>'
(unresolved_decl_ref_expr type='<null>' name=UIWindow specialized=no)
(tuple_expr type='<null>' names=frame
(unresolved_dot_expr type='<null>' field 'bounds'
(call_expr type='<null>'
(unresolved_dot_expr type='<null>' field 'mainScreen'
(unresolved_decl_ref_expr type='<null>' name=UIScreen specialized=no))
(tuple_expr type='<null>'))))))
(sequence_expr type='<null>'
(unresolved_dot_expr type='<null>' field 'backgroundColor'
(force_value_expr type='<null>'
(unresolved_dot_expr type='<null>' field 'window'
(declref_expr type='<null>' decl=AppDelegate.(file).AppDelegate.func decl.self@AppDelegate.swift:17:10 specialized=yes))))
(assign_expr
(**NULL EXPRESSION**)
(**NULL EXPRESSION**))
(call_expr type='<null>'
(unresolved_dot_expr type='<null>' field 'whiteColor'
(unresolved_decl_ref_expr type='<null>' name=UIColor specialized=no))
(tuple_expr type='<null>')))
(call_expr type='<null>'
(unresolved_dot_expr type='<null>' field 'makeKeyAndVisible'
(force_value_expr type='<null>'
(unresolved_dot_expr type='<null>' field 'window'
(declref_expr type='<null>' decl=AppDelegate.(file).AppDelegate.func decl.self@AppDelegate.swift:17:10 specialized=yes))))
(tuple_expr type='<null>'))
(return_stmt
(unresolved_decl_ref_expr type='<null>' name=true specialized=no))))
(func_decl "applicationWillResignActive(_:)" type='<null type>'
(body_params
(pattern_typed implicit
(pattern_named implicit 'self'))
(pattern_tuple
(pattern_typed
(pattern_named 'application')
(type_ident
(component id='UIApplication' bind=none)))))
(brace_stmt))
(func_decl "applicationDidEnterBackground(_:)" type='<null type>'
(body_params
(pattern_typed implicit
(pattern_named implicit 'self'))
(pattern_tuple
(pattern_typed
(pattern_named 'application')
(type_ident
(component id='UIApplication' bind=none)))))
(brace_stmt))
(func_decl "applicationWillEnterForeground(_:)" type='<null type>'
(body_params
(pattern_typed implicit
(pattern_named implicit 'self'))
(pattern_tuple
(pattern_typed
(pattern_named 'application')
(type_ident
(component id='UIApplication' bind=none)))))
(brace_stmt))
(func_decl "applicationDidBecomeActive(_:)" type='<null type>'
(body_params
(pattern_typed implicit
(pattern_named implicit 'self'))
(pattern_tuple
(pattern_typed
(pattern_named 'application')
(type_ident
(component id='UIApplication' bind=none)))))
(brace_stmt))
(func_decl "applicationWillTerminate(_:)" type='<null type>'
(body_params
(pattern_typed implicit
(pattern_named implicit 'self'))
(pattern_tuple
(pattern_typed
(pattern_named 'application')
(type_ident
(component id='UIApplication' bind=none)))))
(brace_stmt))))
由于不了解编译器相关的知识，无法解析上述输出，但是看起来很像common lisp 的“点对”数据结构。
另外，我们会注意到另一个比较重要的命令行参数：-repl，我们一起玩玩，看看这个工具能力怎么样。
在命令行执行如下命令：
xcrun swift -repl
可以得到一个脚本解析器的执行环境：
我们参考“The Swift Programming Language”写一个Hello World，看看效果：
可以使用：Ctrl + D退出解析器。
这里可以得到：
1、swift既可以被编译执行，也可以被解析执行，是真正的动态语言。
2、大家可以用这个工具来学习语言特性。
就分析到这里，希望对大家有帮助。
