一、常用的命令

1.print、po输出打印

打印变量的值可以使用print（简写p）命令，该命令如果打印的是基础数据类型，则会列出基础数据类型的类型和值。如果是对象，还会打印出对象指针地址，如下所示：

(lldb) p str
(__NSCFConstantString *) $1 = 0x000000010c14e068 @"我是一个普通的字符串"
(lldb) p intDemo
(NSInteger) $2 = 2
(lldb)

print命令输出的信息中带有 $0 、 $1的字样。我们可以将它看作是lldb内部的变量，我们可以在后面的查询中直接使用这些值。比如现在我要重新取回 $1 的值（或者调用$1的方法都是可以的，注意在使用lldb内部的变量$来记录变量的时候，没有语法提示，所以你需要自己能准确的打印出方法的名字，或者在Xcode编辑器中去打好方法，然后再拷贝到lldb处）

(lldb) p $1
(__NSCFConstantString *) $1 = 0x000000010c14e068 @"我是一个普通的字符串"

每打印一个与对象相关的命令，$后面的值都会加1

print的打印信息较多，如果只想查看对象的值，则可以使用po（printobject）命令，如下所示：

(lldb)  po str
我是一个普通的字符串

(lldb) po intDemo
2

对于基础数据类型，还可以指定格式打印，如用16进制的格式打印：

(lldb) p/x intDemo
(NSInteger) $14 = 0x0000000000000002

其他格式（如：八进制，二进制等）不做过多说明，感兴趣可以自己研究。

上面的例子是比较简单的，在实际开发中的应用是非常广泛的，如，打印self.view所有的子view，查看某个子view的描述等等。

2.call

call调用方法的意思，和p,po也有此功能，call可以使用在没有返回值，不需要显示输出的情况下，如设置view颜色

(lldb) call [self.view setBackgroundColor:[UIColor redColor]]

这样就不用为了看改一下颜色的效果再进行build一次了，尤其是build一次还要经过漫长的等待。

3.expression表达式(expr)

expr常用于调试时修改变量的值，如进入商品详情页之后，我想使用一个测试商品进行测试，这时，不需要修改代码再重新编译就可以看到效果，来试验一下。我在viewDidLoad中打一个断点，进入商品详情页，到断点位置后，输入expr命令来修改 productId·和skuId,然后继续运行，OK了，省去了写测试代码和编译的时间，事半功倍有没有！

(lldb) expr self.productId = @"A0000001076"
(__NSCFString *) $0 = 0x00007ffc78a8f300 @"A0000001076"
(lldb) expr self.currentSkuId = @"sku10210013"
(__NSCFString *) $1 = 0x00007ffc790610c0 @"sku10210013"

它的作用不仅仅是修改变量的值，你加其他功能的代码也是可以的，只要是和上下文相关的一句代码就OK，如：初始化导航栏之后，我想修改一下它的颜色，看一下效果，如下：

(lldb) expr self.superNavBarView.backgroundColor = [UIColor redColor]
(UICachedDeviceRGBColor *) $3 = 0x00007ffc783d0290

注意：表达式之后不需要加分号，加了分号之后会报错

4.image

（1）image lookup --address寻址，定位异常代码位置

举例说明，下面这段代码，执行的时候必然会出现异常，因为越界了

NSString *str = @"245656";
[str substringFromIndex:10];

控制台输出了以下崩溃信息：

2016-05-27 14:58:54.173 GomeEShop[61425:4544758] *** Terminating app due to uncaught exception 'NSRangeException', reason: '*** -[__NSCFConstantString substringFromIndex:]: Index 10 out of bounds; string length 6'
*** First throw call stack:
(
    0   CoreFoundation                      0x000000010e99ad85 __exceptionPreprocess + 165
    1   libobjc.A.dylib                     0x000000011360ddeb objc_exception_throw + 48
    2   CoreFoundation                      0x000000010e99acbd +[NSException raise:format:] + 205
    3   Foundation                          0x000000010f8698bd -[NSString substringFromIndex:] + 126
    4   GomeEShop                           0x00000001097c396f -[GMFPTGoodsDetailVC initNecessaryViews] + 3903
    5   GomeEShop                           0x00000001097c1c51 -[GMFPTGoodsDetailVC viewDidLoad] + 369
    6   UIKit                               0x00000001110ae984 -[UIViewController loadViewIfRequired] + 1198
    7   UIKit                               0x00000001110b493b -[UIViewController __viewWillAppear:] + 120
    8   UIKit                               0x00000001110e4750 -[UINavigationController _startCustomTransition:] + 1203
    9   UIKit                               0x00000001110f4b9b -[UINavigationController _startDeferredTransitionIfNeeded:] + 712
    10  UIKit                               0x00000001110f5d0b -[UINavigationController __viewWillLayoutSubviews] + 57
    11  UIKit                               0x00000001112a4503 -[UILayoutContainerView layoutSubviews] + 248
    12  UIKit                               0x0000000110fce980 -[UIView(CALayerDelegate) layoutSublayersOfLayer:] + 703
    13  QuartzCore                          0x0000000110c85c00 -[CALayer layoutSublayers] + 146
    14  QuartzCore                          0x0000000110c7a08e _ZN2CA5Layer16layout_if_neededEPNS_11TransactionE + 366
    15  QuartzCore                          0x0000000110c79f0c _ZN2CA5Layer28layout_and_display_if_neededEPNS_11TransactionE + 24
    16  QuartzCore                          0x0000000110c6e3c9 _ZN2CA7Context18commit_transactionEPNS_11TransactionE + 277
    17  QuartzCore                          0x0000000110c9c086 _ZN2CA11Transaction6commitEv + 486
    18  UIKit                               0x0000000110f4019b _afterCACommitHandler + 174
    19  CoreFoundation                      0x000000010e8bfc37 __CFRUNLOOP_IS_CALLING_OUT_TO_AN_OBSERVER_CALLBACK_FUNCTION__ + 23
    20  CoreFoundation                      0x000000010e8bfba7 __CFRunLoopDoObservers + 391
    21  CoreFoundation                      0x000000010e8b57fb __CFRunLoopRun + 1147
    22  CoreFoundation                      0x000000010e8b50f8 CFRunLoopRunSpecific + 488
    23  GraphicsServices                    0x000000011481bad2 GSEventRunModal + 161
    24  UIKit                               0x0000000110f13f09 UIApplicationMain + 171
    25  GomeEShop                           0x00000001091c0ebf main + 111
    26  libdyld.dylib                       0x0000000113ba992d start + 1
)
libc++abi.dylib: terminating with uncaught exception of type NSException

通过异常信息，我们看到崩溃很可能发生在-[GMFPTGoodsDetailVCinitNecessaryViews]方法中，也就是地址0x00000001097c396f,我们输入以下命令来进行精确定位

(lldb) image lookup --address 0x00000001097c396f

执行后输出以下信息

Address: GomeEShop[0x00000001006af96f] (GomeEShop.__TEXT.__text + 7000239)
Summary: GomeEShop`-[GMFPTGoodsDetailVC initNecessaryViews] + 3903 at GMFPTGoodsDetailVC.m:589

我们看到出错的位置在GMFPTGoodsDetailVC.m文件中的initNecessaryViews方法中，第589行

（2）image lookup --type查看类型

我们还可以使用image lookup命令来查看具体的类型，如下所示：

(lldb) image lookup --type UIImage

执行后输出了UIImage所包含的属性

Best match found in /Users/zhangbeibei/Library/Developer/Xcode/DerivedData/GomeEShop-dhpyydtykrwzvpawiualtxfthsqy/Build/Products/Debug-iphonesimulator/GomeEShop.app/GomeEShop:
id = {0x00cabeb2}, name = "UIImage", byte-size = 8, decl = UIImage.h:53, compiler_type = "@interface UIImage : NSObject
@property ( readonly,getter = size,setter = <null selector>,nonatomic ) CGSize size;
@property ( readonly,getter = CGImage,setter = <null selector>,nonatomic ) CGImageRef CGImage;
@property ( readonly,getter = CIImage,setter = <null selector>,nonatomic ) CIImage * CIImage;
@property ( readonly,getter = imageOrientation,setter = <null selector>,nonatomic ) UIImageOrientation imageOrientation;
@property ( readonly,getter = scale,setter = <null selector>,nonatomic ) CGFloat scale;
@property ( readonly,getter = images,setter = <null selector>,nonatomic ) NSArray * images;
@property ( readonly,getter = duration,setter = <null selector>,nonatomic ) NSTimeInterval duration;
@property ( readonly,getter = capInsets,setter = <null selector>,nonatomic ) UIEdgeInsets capInsets;
@property ( readonly,getter = resizingMode,setter = <null selector>,nonatomic ) UIImageResizingMode resizingMode;
@property ( readonly,getter = alignmentRectInsets,setter = <null selector>,nonatomic ) UIEdgeInsets alignmentRectInsets;
@property ( readonly,getter = renderingMode,setter = <null selector>,nonatomic ) UIImageRenderingMode renderingMode;
@property ( readonly,getter = traitCollection,setter = <null selector>,copy,nonatomic ) UITraitCollection * traitCollection;
@property ( readonly,getter = imageAsset,setter = <null selector>,nonatomic ) UIImageAsset * imageAsset;
@property ( readonly,getter = flipsForRightToLeftLayoutDirection,setter = <null selector>,nonatomic ) BOOL flipsForRightToLeftLayoutDirection;
@end"

5.bt

我们可以用bt来打印调用堆栈，加all可打印多有thread的堆栈，如下图

(lldb) bt
* thread #1: tid = 0x4558f6, 0x0000000113eedf06 libsystem_kernel.dylib`__pthread_kill + 10, queue = 'com.apple.main-thread', stop reason = signal SIGABRT
    frame #0: 0x0000000113eedf06 libsystem_kernel.dylib`__pthread_kill + 10
    frame #1: 0x0000000113eb54ec libsystem_pthread.dylib`pthread_kill + 90
    frame #2: 0x0000000113c4fcec libsystem_c.dylib`abort + 129
    frame #3: 0x0000000113a4e051 libc++abi.dylib`abort_message + 257
    frame #4: 0x0000000113a73ac9 libc++abi.dylib`default_terminate_handler() + 267
    frame #5: 0x000000011360e046 libobjc.A.dylib`_objc_terminate() + 103
    frame #6: 0x0000000113a7126e libc++abi.dylib`std::__terminate(void (*)()) + 8
    frame #7: 0x0000000113a70ef9 libc++abi.dylib`__cxa_rethrow + 99
    frame #8: 0x000000011360df5e libobjc.A.dylib`objc_exception_rethrow + 40
    frame #9: 0x000000010e8b51b4 CoreFoundation`CFRunLoopRunSpecific + 676
    frame #10: 0x000000011481bad2 GraphicsServices`GSEventRunModal + 161
    frame #11: 0x0000000110f13f09 UIKit`UIApplicationMain + 171
  * frame #12: 0x00000001091c0ebf GomeEShop`main(argc=1, argv=0x00007fff56aea5f8) + 111 at main.m:16
    frame #13: 0x0000000113ba992d libdyld.dylib`start + 1
    frame #14: 0x0000000113ba992d libdyld.dylib`start + 1

二、断点编辑

1.设置触发条件

我们在进行断点调试时，可以为断点设置触发条件，以便针对特定的数据进行分析，观察程序运行正常，如在首页的403行设置一个断点，触发条件是isCache为NO

3B72A5A4-900E-4A3F-A220-19EDE283B479.png

这样当刷新数据且数据是从缓存中读取的时候，该断点生效

2.设置触发事件

在编辑断点时从Action选项列表中可以看到，断点的触发事件有AppleScript、Capture GPU Frame、Debugger Command、Log Message、Shell Command、Sound这几种。

Debugger Command

它和上述说的在控制台输入的命令是一样的，可以起到相同的效果，但是它的方便之处在于，如果你勾选了Automatically continue after evaluating actions，在断点处程序不会中断，会正常运行。不足之处是，输入命令时没有联想提示，不太方便。

如下图，在加载首页数据时的断点处，添加了命令expr self.superNavBarView.backgroundColor = [UIColor blueColor]，再勾选上Automatically continue after evaluating actions，执行到此处的时候不会停止，而且导航栏的颜色变成了蓝色。

06568158-2E33-42A9-9D38-80382B4A7AF1.png

使用Debugger Command，再加po命令可以随心所欲的输出你需要的信息，而你就不用为了调试一个东西而加一句NSLog然后再重新编译一次看结果了，代码中也少了很多NSLog这样的语句，是不是简洁多了。

D851726B-4C7E-40B9-AAE5-985A74A6AE0D.png

注意：经试验在这里输出格式化字符串时，不能使用[NSString stringWithFormat:@"%@",str]，否则会报下面的错误，要使用上图中的[[NSString alloc] initWithFormat:@"%@",str]才可以，是不是有点怪

error: too many arguments to method call, expected 1, have 2
error: 1 errors parsing expression

Log Message

看字面意思就知道这个是输出log，在输入框中直接输入你想输出的内容接，比Debugger Command+po方便，但是它很直白，不能输出变量等信息，只能输出静态字符串，如下图，输出的内容就是输入的内容，不会被格式化

AE35AA23-C67D-4243-A0BA-9F8FA62A35FE.png

输出内容就是[[NSString alloc] initWithFormat:@"%@",str]

Sound

设置声音，当代码执行到断点处时，会有提示音，对我们来说不是经常用

其他几种就不做探究了，因为我也不是很懂，呵呵。。。

三、命令的简称和别名

1.简称

很多时候，LLDB完整的命令是很长的。比如前面所说的image lookup --address这个组合命令。为了方便日常的使用，提高效率，LLDB命令也提供通过简称的方式调用命令。如 image lookup —address这个 命令，可以简写为im loo -a，expression简写为expr，print简写为p等等，自己去发现吧。

2.别名

除了使用命令的简称外，对于不好记忆的命令，我们还可以为它设置别名，现在我们为imagelookup –address设置一个别名叫imgadd

输入命令：

command alias imgadd image lookup --address %1

然后再使用imgadd命令和imagelookup –address就是一样的了，不过我发现比较坑的是，重新编译一次工程后，设置的别名就不好使了，还是使用原名吧，在Xcode控制台输入命令时都会有联想提示，也比较方便

以上介绍的命令是比较常用的一些，然而lldb的命令远不只有这些，想知道还有哪些，输入help，查看一下

(lldb) help
Debugger commands:

  apropos           -- Find a list of debugger commands related to a particular
                       word/subject.
  breakpoint        -- A set of commands for operating on breakpoints. Also see
                       _regexp-break.
  bugreport         -- Set of commands for creating domain specific bugreports.
  command           -- A set of commands for managing or customizing the
                       debugger commands.
  disassemble       -- Disassemble bytes in the current function, or elsewhere
                       in the executable program as specified by the user.
  expression        -- Evaluate an expression (ObjC++ or Swift) in the current
                       program context, using user defined variables and
                       variables currently in scope.
  frame             -- A set of commands for operating on the current thread's
                       frames.
  gdb-remote        -- Connect to a remote GDB server.  If no hostname is
                       provided, localhost is assumed.
  gui               -- Switch into the curses based GUI mode.
  help              -- Show a list of all debugger commands, or give details
                       about specific commands.
  kdp-remote        -- Connect to a remote KDP server.  udp port 41139 is the
                       default port number.
  language          -- A set of commands for managing language-specific
                       functionality.'.
  log               -- A set of commands for operating on logs.
  memory            -- A set of commands for operating on memory.
  platform          -- A set of commands to manage and create platforms.
  plugin            -- A set of commands for managing or customizing plugin
                       commands.
  process           -- A set of commands for operating on a process.
  quit              -- Quit out of the LLDB debugger.
  register          -- A set of commands to access thread registers.
  script            -- Pass an expression to the script interpreter for
                       evaluation and return the results. Drop into the
                       interactive interpreter if no expression is given.
  settings          -- A set of commands for manipulating internal settable
                       debugger variables.
  source            -- A set of commands for accessing source file information
  target            -- A set of commands for operating on debugger targets.
  thread            -- A set of commands for operating on one or more threads
                       within a running process.
  type              -- A set of commands for operating on the type system
  version           -- Show version of LLDB debugger.
  watchpoint        -- A set of commands for operating on watchpoints.

Current command abbreviations (type 'help command alias' for more info):

  add-dsym  -- ('target symbols add')  Add a debug symbol file to one of the
               target's current modules by specifying a path to a debug symbols
               file, or using the options to specify a module to download
               symbols for.
  attach    -- ('_regexp-attach')  Attach to a process id if in decimal,
               otherwise treat the argument as a process name to attach to.
  b         -- ('_regexp-break')  Set a breakpoint using a regular expression
               to specify the location, where <linenum> is in decimal and
               <address> is in hex.
  bt        -- ('_regexp-bt')  Show a backtrace.  An optional argument is
               accepted; if that argument is a number, it specifies the number
               of frames to display.  If that argument is 'all', full
               backtraces of all threads are displayed.
  c         -- ('process continue')  Continue execution of all threads in the
               current process.
  call      -- ('expression --')  Evaluate an expression (ObjC++ or Swift) in
               the current program context, using user defined variables and
               variables currently in scope.
  continue  -- ('process continue')  Continue execution of all threads in the
               current process.
  detach    -- ('process detach')  Detach from the current process being
               debugged.
  di        -- ('disassemble')  Disassemble bytes in the current function, or
               elsewhere in the executable program as specified by the user.
  dis       -- ('disassemble')  Disassemble bytes in the current function, or
               elsewhere in the executable program as specified by the user.
  display   -- ('_regexp-display')  Add an expression evaluation stop-hook.
  down      -- ('_regexp-down')  Go down "n" frames in the stack (1 frame by
               default).
  env       -- ('_regexp-env')  Implements a shortcut to viewing and setting
               environment variables.
  exit      -- ('quit')  Quit out of the LLDB debugger.
  f         -- ('frame select')  Select a frame by index from within the
               current thread and make it the current frame.
  file      -- ('target create')  Create a target using the argument as the
               main executable.
  finish    -- ('thread step-out')  Finish executing the function of the
               currently selected frame and return to its call site in
               specified thread (current thread, if none specified).
  image     -- ('target modules')  A set of commands for accessing information
               for one or more target modules.
  j         -- ('_regexp-jump')  Sets the program counter to a new address.
  jump      -- ('_regexp-jump')  Sets the program counter to a new address.
  kill      -- ('process kill')  Terminate the current process being debugged.
  l         -- ('_regexp-list')  Implements the GDB 'list' command in all of
               its forms except FILE:FUNCTION and maps them to the appropriate
               'source list' commands.
  list      -- ('_regexp-list')  Implements the GDB 'list' command in all of
               its forms except FILE:FUNCTION and maps them to the appropriate
               'source list' commands.
  n         -- ('thread step-over')  Source level single step in specified
               thread (current thread, if none specified), stepping over calls.
  next      -- ('thread step-over')  Source level single step in specified
               thread (current thread, if none specified), stepping over calls.
  nexti     -- ('thread step-inst-over')  Single step one instruction in
               specified thread (current thread, if none specified), stepping
               over calls.
  ni        -- ('thread step-inst-over')  Single step one instruction in
               specified thread (current thread, if none specified), stepping
               over calls.
  p         -- ('expression --')  Evaluate an expression (ObjC++ or Swift) in
               the current program context, using user defined variables and
               variables currently in scope.
  po        -- ('expression -O  -- ')  Evaluate an expression (ObjC++ or Swift)
               in the current program context, using user defined variables and
               variables currently in scope.
  print     -- ('expression --')  Evaluate an expression (ObjC++ or Swift) in
               the current program context, using user defined variables and
               variables currently in scope.
  q         -- ('quit')  Quit out of the LLDB debugger.
  r         -- ('process launch -X true --')  Launch the executable in the
               debugger.
  rbreak    -- ('breakpoint set -r %1')  Sets a breakpoint or set of
               breakpoints in the executable.
  repl      -- ('expression -r  -- ')  Evaluate an expression (ObjC++ or Swift)
               in the current program context, using user defined variables and
               variables currently in scope.
  run       -- ('process launch -X true --')  Launch the executable in the
               debugger.
  s         -- ('thread step-in')  Source level single step in specified thread
               (current thread, if none specified).
  si        -- ('thread step-inst')  Single step one instruction in specified
               thread (current thread, if none specified).
  step      -- ('thread step-in')  Source level single step in specified thread
               (current thread, if none specified).
  stepi     -- ('thread step-inst')  Single step one instruction in specified
               thread (current thread, if none specified).
  t         -- ('thread select')  Select a thread as the currently active
               thread.
  tbreak    -- ('_regexp-tbreak')  Set a one shot breakpoint using a regular
               expression to specify the location, where <linenum> is in
               decimal and <address> is in hex.
  undisplay -- ('_regexp-undisplay')  Remove an expression evaluation
               stop-hook.
  up        -- ('_regexp-up')  Go up "n" frames in the stack (1 frame by
               default).
  x         -- ('memory read')  Read from the memory of the process being
               debugged.

For more information on any command, type 'help <command-name>'.

正如上述最后一句所说，想了解某个命令的更多信息，输入help +命令名即可

命令是不是太多了，想要熟练使用，就要多用多用再多用，熟练之后效率会有意想不到的提高!