LLDB是个开源的内置于XCode的调试工具，这里来理一理常用用法。
lldb对于命令的简称，是头部匹配方式，只要不混淆，你可以随意简称某个命令。结果为在xcode下验证所得，可能与其它平台有所误差。
1 打印值、修改值、调用方法
1.1 p、po 打印值
打印相关的命令有：p、po。
p 和 po 的区别在于使用 po 只会输出对应的值，而 p 则会返回值的类型以及命令结果的引用名。
(lldb) p width
(CGFloat) $10 = 70
(lldb) po width
70
(lldb) p endTime
(__NSCFString *) $14 = 0x0000608000437660 @"08-11 11:43"
(lldb) po endTime
08-11 11:43对比结果:
po：输出值
p：输出值+值类型+引用名+内存地址(xcode中有内存地址，其它平台不确定)
除此之外，p还隐藏了一个有意思的功能，常量的进制转换:
//默认打印为10进制
(lldb) p 100
(int) $8 = 100
//转16进制
(lldb) p/x 100
(int) $9 = 0x00000064
//转8进制
(lldb) p/o 100
(int) $10 = 0144
//转二进制
(lldb) p/t 100
(int) $2 = 0b00000000000000000000000001100100
//字符转10进制数字
(lldb) p/d 'A'
(char) $7 = 65
//10进制数字转字符
(lldb) p/c 66
(int) $10 = B 1.2 expression 修改参数值
感觉exp命令是调试过程中最有价值有命令了，它可以打印值、修改值。
//expression打印值
(lldb) expression width
(CGFloat) $5 = 67
//expression修改值
(lldb) expression width = 80
(CGFloat) $6 = 80
//打印修改后结果
(lldb) p width
(CGFloat) $7 = 80
(lldb)expression：同样可以输出值+值类型+引用名，但其一般用于修改。
1.3 call 方法调用
在断点调用某个方法，并输出此方法的返回值。
(lldb) call width
(CGFloat) $12 = 70
(lldb) call endTime
(__NSCFString *) $16 = 0x0000608000437660 @"08-11 11:43"call：同样为输出值+值类型+引用名
2 Thread
2.1 堆栈打印 thread backtrace
如果嫌堆栈打印太长，可以加一个值限制，如bt 10，只打印
(lldb) bt 10
* thread #1, queue = 'com.apple.main-thread', stop reason = breakpoint 1.1
* frame #0: 0x00000001005e4906 DiDi`-[FW_HomeCell_HotBill setDataSource:](self=0x00007fd3938a7800, _cmd="setDataSource:", dataSource=0x00006080001c8bb0) at FW_HomeCell.m:357
frame #1: 0x00000001009a9fd7 DiDi`-[FW_MyHomeTableView tableView:cellForRowAtIndexPath:](self=0x00007fd3921fec00, _cmd="tableView:cellForRowAtIndexPath:", tableView=0x00007fd3921fec00, indexPath=0xc000000000000316) at FW_MyHomeTableView.m:247
frame #2: 0x00000001055a2ab2 UIKit`-[UITableView _createPreparedCellForGlobalRow:withIndexPath:willDisplay:] + 750
frame #3: 0x00000001055a2cf8 UIKit`-[UITableView _createPreparedCellForGlobalRow:willDisplay:] + 74
frame #4: 0x0000000105577639 UIKit`-[UITableView _updateVisibleCellsNow:isRecursive:] + 2845
frame #5: 0x00000001055abccc UIKit`-[UITableView _performWithCachedTraitCollection:] + 111
frame #6: 0x0000000105592e7a UIKit`-[UITableView layoutSubviews] + 233
frame #7: 0x00000001054f955b UIKit`-[UIView(CALayerDelegate) layoutSublayersOfLayer:] + 1268
frame #8: 0x0000000105114904 QuartzCore`-[CALayer layoutSublayers] + 146
frame #9: 0x0000000105108526 QuartzCore`CA::Layer::layout_if_needed(CA::Transaction*) + 3702.2 thread return 跳出当前方法的执行
Debug的时候，也许会因为各种原因，我们不想让代码执行某个方法，或者要直接返回一个想要的值。这时候就该thread return上场了。
有返回值的方法里，如：numberOfSectionsInTableView:，直接thread return 10，就可以直接跳过方法执行，返回10.
//跳出方法
(lldb) thread return
//让带有返回int值的方法直接跳出，并返回值10
(lldb) thread return 102.3 流程控制
实际上使用xcode自带的可视化工具来控制“继续”“暂停”“下一步”“进入”“跳出”更简单
继续：continue, c
下一步：next, n
进入：step, s
跳出：finish, f2.4 跳帧 frame select N
2.1中打印有10帧，如果我想跳转到第1帧：frame select 1
(lldb) frame select 1
frame #1: 0x0000000105e91c3c DiDi`-[FW_HomeViewController tableView:cellForRowAtIndexPath:](self=0x00007fbf9f73b410, _cmd="tableView:cellForRowAtIndexPath:", tableView=0x00007fbfa11dc400, indexPath=0xc000000000a00316) at FW_HomeViewController.m:597
594 break;
595
596 case 3: {
-> 597 cell.[4md[0mataSource = _hotBills[indexPath.row];
598 cell.textSelect = ^(UITextField *text) {
599 weakSelf.curruntText = text;
600 };2.5 查看帧变量 frame variable
(lldb) frame variable
(FW_HomeViewController *) self = 0x00007faccbf587d0
(SEL) _cmd = "tableView:cellForRowAtIndexPath:"
(UITableView *) tableView = 0x00007faccd09b400
(NSIndexPath *) indexPath = 0xc000000000000316
(FW_HomeViewController *) weakSelf = 0x00007faccbf587d0
(FW_HomeCell_HotBill *) cell = 0x00007faccc101a00
(UIView *) model = 0x00007fff52c13d90
(FW_HomeCell_HotBill *) billCell = 0x00000001124e99f63 Image
3.1 image lookup -address 查找崩溃位置
当你遇见数组崩溃，你又没有找到崩溃的位置，只扔给你一堆报错信息，这时候image lookup来帮助你。如下
0 CoreFoundation 0x0000000103209b0b __exceptionPreprocess + 171
1 libobjc.A.dylib 0x00000001079db141 objc_exception_throw + 48
2 CoreFoundation 0x000000010313effb -[__NSArrayM objectAtIndex:] + 203
3 DiDi 0x00000001009a9f3a -[FW_MyHomeTableView tableView:cellForRowAtIndexPath:] + 1322
4 UIKit 0x00000001055a2ab2 -[UITableView _createPreparedCellForGlobalRow:withIndexPath:willDisplay:] + 750
5 UIKit 0x00000001055a2cf8 -[UITableView _createPreparedCellForGlobalRow:willDisplay:] + 74
6 UIKit 0x0000000105577639 -[UITableView _updateVisibleCellsNow:isRecursive:] + 2845
7 UIKit 0x00000001055abccc -[UITableView _performWithCachedTraitCollection:] + 111
8 UIKit 0x0000000105592e7a -[UITableView layoutSubviews] + 233
9 UIKit 0x00000001054f955b -[UIView(CALayerDelegate) layoutSublayersOfLayer:] + 1268
10 QuartzCore 0x0000000105114904 -[CALayer layoutSublayers] + 146寻找自己项目的标识，看到frame3位置，你只需这样查找位置：
image lookup -a 0x00000001009a9f3a
Address: DiDi[0x0000000100609f3a] (DiDi.__TEXT.__text + 6323194)
Summary: DiDi`-[FW_MyHomeTableView tableView:cellForRowAtIndexPath:] + 1322 at FW_MyHomeTableView.m:243项目中FW_MyHomeTableView.m:243，perfect!
3.2 image lookup -name 查找方法来源
此命令可以用来查找方法的来源。包括在第三方SDK中的方法，也能被查到。
例：查找transformOtherModelToSuit:
(lldb) image lookup -n transformOtherModelToSuit:
1 match found in /Users/xxx/Library/Developer/Xcode/DerivedData/DiDi-cwpbvvyvqmeijmcjnneothzuthsy/Build/Products/Debug-iphonesimulator/DiDi.app/DiDi:
Address: DiDi[0x0000000100293d60] (DiDi.__TEXT.__text + 2693664)
Summary: DiDi`+[FW_BetFunction transformOtherModelToSuit:] at FW_BetFunction.m:1073.3 image lookup –type 查看成员
查看某个class的所有属性和成员变量。不过貌似frameWork库中文件不能查看。
(lldb) image lookup -t MatchEvent
1 match found in /Users/xxxx/Library/Developer/Xcode/DerivedData/DiDi-cwpbvvyvqmeijmcjnneothzuthsy/Build/Products/Debug-iphonesimulator/DiDi.app/DiDi:
id = {0x00433d32}, name = "MatchEvent", byte-size = 48, decl = MatchEvent.h:11, compiler_type = "@interface MatchEvent : NSObject{
BOOL _isHome;
NSString * _playerName;
NSString * _timePoint;
NSString * _eventType;
NSString * _eventDesc;
}
@property ( getter = isHome,setter = setIsHome:,assign,readwrite,nonatomic ) BOOL isHome;
@property ( getter = playerName,setter = setPlayerName:,readwrite,copy,nonatomic ) NSString * playerName;
@property ( getter = timePoint,setter = setTimePoint:,readwrite,copy,nonatomic ) NSString * timePoint;
@property ( getter = eventType,setter = setEventType:,readwrite,copy,nonatomic ) NSString * eventType;
@property ( getter = eventDesc,setter = setEventDesc:,readwrite,copy,nonatomic ) NSString * eventDesc;
@end"4 breakpoint
4.1 文件名+行号 breakpoint set -f xxx -l xxx
我们平时操作xcode，在某一行点下断点，其实操作的就是这个命令。
(lldb) breakpoint set -f FW_ProfilesDetailModel.m -l 95
Breakpoint 3: where = DiDi`-[FW_ProfilesDetailModel incomeRate] + 27 at FW_ProfilesDetailModel.m:96, address = 0x0000000105b404bb4.2 函数名断点
4.2.1 方法名断点 breakpoint set -n 方法名
(lldb) breakpoint set -n viewDidLoad
Breakpoint 4: 414 locations.Tips:这里要说一下，xcode其实也有函数名断点，不过用breakpoint set -n实现，比xcode下断点快N倍，不过xcode下的断点还给提示所有断到的位置。
4.2.2 类中方法断点 breakpoint set -n “-[类名 方法名]”
(lldb) breakpoint set -n "-[FW_MyHomeViewController viewDidLoad]"
Breakpoint 8: where = DiDi`-[FW_MyHomeViewController viewDidLoad] + 20 at FW_MyHomeViewController.m:58, address = 0x0000000105aec944注意：-[FW_MyHomeViewController viewDidLoad]，外面一定要加双引
号，不然会误识别为-[FW_MyHomeViewController`
4.3 条件断点 breakpoint set -c “xxxx”
和xcode中symbolic Breakpoint功能相同，我在FW_HomeCell.m 362行下断点，但又想过滤仅width>68的状态，操作如下：
breakpoint set -f FW_HomeCell.m -l 362 -c "width > 68"
Breakpoint 5: where = DiDi`-[FW_HomeCell_HotBill setDataSource:] + 2006 at FW_HomeCell.m:363, address = 0x000000010d22e0a64.4 查看断点列表 breakpoint list
(lldb) breakpoint list
Current breakpoints:
8: name = '-[FW_MyHomeViewController viewDidLoad]', locations = 1, resolved = 1, hit count = 2
8.1: where = DiDi`-[FW_MyHomeViewController viewDidLoad] + 20 at FW_MyHomeViewController.m:58, address = 0x0000000105aec944, resolved, hit count = 2
9: file = '/Users/xxxx/didi-ios/DiDi/FollowWinner/Model/FW_HomeModel.m', line = 24, exact_match = 0, locations = 1, resolved = 1, hit count = 0
9.1: where = DiDi`+[FW_HomeModel_Rank parasWithDict:limitNickLength:] + 89 at FW_HomeModel.m:24, address = 0x00000001061bc169, resolved, hit count = 04.5 禁用/启用断点 breakpoint disable/enable
//禁用断点
(lldb) breakpoint disable 9
1 breakpoints disabled.
(lldb) breakpoint list
Current breakpoints:
9: file = '/Users/zmz/didi-ios/DiDi/FollowWinner/Model/FW_HomeModel.m', line = 24, exact_match = 0, locations = 1 Options: disabled
9.1: where = DiDi`+[FW_HomeModel_Rank parasWithDict:limitNickLength:] + 89 at FW_HomeModel.m:24, address = 0x00000001061bc169, unresolved, hit count = 0
//启用断点
(lldb) breakpoint enable 9
1 breakpoints enabled.
(lldb) breakpoint list
Current breakpoints:
9: file = '/Users/zmz/didi-ios/DiDi/FollowWinner/Model/FW_HomeModel.m', line = 24, exact_match = 0, locations = 1, resolved = 1, hit count = 0
9.1: where = DiDi`+[FW_HomeModel_Rank parasWithDict:limitNickLength:] + 89 at FW_HomeModel.m:24, address = 0x00000001061bc169, resolved, hit count = 04.6 移除断点 breakpoint delete
(lldb) breakpoint delete 8
1 breakpoints deleted; 0 breakpoint locations disabled.
(lldb) breakpoint list
Current breakpoints:
9: file = '/Users/xxxx/didi-ios/DiDi/FollowWinner/Model/FW_HomeModel.m', line = 24, exact_match = 0, locations = 1, resolved = 1, hit count = 0
9.1: where = DiDi`+[FW_HomeModel_Rank parasWithDict:limitNickLength:] + 89 at FW_HomeModel.m:24, address = 0x00000001061bc169, resolved, hit count = 0结语：
有了这些命令，调试起来肯定就得心应手了。总结下常用的，供多看几遍加深回忆：
堆栈相关：bt查看堆栈、frame select跳帧、frame variable查看帧参数、thread return跳出当前执行、【step/finish/next/continue】进入/跳出/下一步/跳出本断点
断点相关：breakpoint set -f -l -c条件断点、breakpoint set -n方法断点、breakpoint delete断点移除、breakpoint list断点列表
image命令：image lookup -address崩溃定位、image lookup -name方法来源、 image lookup –type 查看成员
LLDB支持简写