iOS之LLDB常用調試命令

LLDB是個開源的內置於XCode的調試工具，這裡來理一理常用用法。
lldb對於命令的簡稱，是頭部匹配方式，只要不混淆，你可以隨意簡稱某個命令。結果為在xcode下驗證所得，可能與其它平臺有所誤差。

1 列印值、修改值、調用方法1.1 p、po 列印值

列印相關的命令有：p、po。
p 和 po 的區別在於使用 po 只會輸出對應的值，而 p 則會返回值的類型以及命令結果的引用名。

(lldb) p width(CGFloat) $10 = 70(lldb) po width70(lldb) p endTime(__NSCFString *) $14 = 0x0000608000437660 @"08-11 11:43"(lldb) po endTime08-11 11:43

對比結果:

po：輸出值
p：輸出值+值類型+引用名+內存地址(xcode中有內存地址，其它平臺不確定)
除此之外，p還隱藏了一個有意思的功能，常量的進位轉換:

//默認列印為10進位(lldb) p 100(int) $8 = 100//轉16進位(lldb) p/x 100(int) $9 = 0x00000064//轉8進位(lldb) p/o 100(int) $10 = 0144//轉二進位(lldb) p/t 100(int) $2 = 0b00000000000000000000000001100100//字符轉10進位數字(lldb) p/d 'A'(char) $7 = 65//10進位數字轉字符(lldb) p/c 66(int) $10 = B\0\0\0

1.2 expression 修改參數值

感覺exp命令是調試過程中最有價值有命令了，它可以列印值、修改值。

//expression列印值(lldb) expression width(CGFloat) $5 = 67//expression修改值(lldb) expression width = 80(CGFloat) $6 = 80//列印修改後結果(lldb) p width(CGFloat) $7 = 80(lldb)

expression：同樣可以輸出值+值類型+引用名，但其一般用於修改。

1.3 call 方法調用

在斷點調用某個方法，並輸出此方法的返回值。

(lldb) call width(CGFloat) $12 = 70(lldb) call endTime(__NSCFString *) $16 = 0x0000608000437660 @"08-11 11:43"

call：同樣為輸出值+值類型+引用名

2 Thread2.1 堆棧列印 thread backtrace

如果嫌堆棧列印太長，可以加一個值限制，如bt 10，只列印

(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*) + 370

2.2 thread return 跳出當前方法的執行

Debug的時候，也許會因為各種原因，我們不想讓代碼執行某個方法，或者要直接返回一個想要的值。這時候就該thread return上場了。
有返回值的方法裡，如：numberOfSectionsInTableView:，直接thread return 10，就可以直接跳過方法執行，返回10.

//跳出方法(lldb) thread return//讓帶有返回int值的方法直接跳出，並返回值10(lldb) thread return 10

2.3 流程控制

實際上使用xcode自帶的可視化工具來控制「繼續」「暫停」「下一步」「進入」「跳出」更簡單

繼續：continue, c下一步：next, n進入：step, s跳出：finish, f

2.4 跳幀 frame select N

2.1中列印有10幀，如果我想跳轉到第1幀：frame select 1

(lldb) frame select 1frame #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 查看幀變量 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 = 0x00000001124e99f6

3 Image3.1 image lookup -address 查找崩潰位置

當你遇見數組崩潰，你又沒有找到崩潰的位置，只扔給你一堆報錯信息，這時候image lookup來幫助你。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

尋找自己項目的標識，看到frame3位置，你只需這樣查找位置：

image lookup -a 0x00000001009a9f3a      Address: DiDi[0x0000000100609f3a] (DiDi.__TEXT.__text + 6323194)      Summary: DiDi`-[FW_MyHomeTableView tableView:cellForRowAtIndexPath:] + 1322 at FW_MyHomeTableView.m:243

項目中FW_MyHomeTableView.m:243，perfect!

3.2 image lookup -name 查找方法來源

此命令可以用來查找方法的來源。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:107

3.3 image lookup –type 查看成員

查看某個class的所有屬性和成員變量。不過貌似frameWork庫中文件不能查看。

(lldb) image lookup -t MatchEvent1 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 breakpoint4.1 文件名+行號 breakpoint set -f xxx -l xxx

我們平時操作xcode，在某一行點下斷點，其實操作的就是這個命令。

(lldb) breakpoint set -f FW_ProfilesDetailModel.m -l 95Breakpoint 3: where = DiDi`-[FW_ProfilesDetailModel incomeRate] + 27 at FW_ProfilesDetailModel.m:96, address = 0x0000000105b404bb

4.2 函數名斷點4.2.1 方法名斷點 breakpoint set -n 方法名

(lldb) breakpoint set -n viewDidLoadBreakpoint 4: 414 locations.

Tips:這裡要說一下，xcode其實也有函數名斷點，不過用breakpoint set -n實現，比xcode下斷點快N倍，不過xcode下的斷點還給提示所有斷到的位置。

4.2.2 類中方法斷點 breakpoint set -n 「-[類名 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]，外面一定要加雙引

號，不然會誤識別為-[FW_MyHomeViewController`

4.3 條件斷點 breakpoint set -c 「xxxx」

和xcode中symbolic Breakpoint功能相同，我在FW_HomeCell.m 362行下斷點，但又想過濾僅width>68的狀態，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 = 0x000000010d22e0a6

4.4 查看斷點列表 breakpoint list

(lldb) breakpoint listCurrent breakpoints:8: name = '-[FW_MyHomeViewController viewDidLoad]', locations = 1, resolved = 1, hit count = 28.1: 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 = 09.1: where = DiDi`+[FW_HomeModel_Rank parasWithDict:limitNickLength:] + 89 at FW_HomeModel.m:24, address = 0x00000001061bc169, resolved, hit count = 0

4.5 禁用/啟用斷點 breakpoint disable/enable

//禁用斷點(lldb) breakpoint disable 91 breakpoints disabled.(lldb) breakpoint listCurrent 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//啟用斷點(lldb) breakpoint enable 91 breakpoints enabled.(lldb) breakpoint listCurrent breakpoints:9: file = '/Users/zmz/didi-ios/DiDi/FollowWinner/Model/FW_HomeModel.m', line = 24, exact_match = 0, locations = 1, resolved = 1, hit count = 09.1: where = DiDi`+[FW_HomeModel_Rank parasWithDict:limitNickLength:] + 89 at FW_HomeModel.m:24, address = 0x00000001061bc169, resolved, hit count = 0

4.6 移除斷點 breakpoint delete

(lldb) breakpoint delete 81 breakpoints deleted; 0 breakpoint locations disabled.(lldb) breakpoint listCurrent breakpoints:9: file = '/Users/xxxx/didi-ios/DiDi/FollowWinner/Model/FW_HomeModel.m', line = 24, exact_match = 0, locations = 1, resolved = 1, hit count = 09.1: where = DiDi`+[FW_HomeModel_Rank parasWithDict:limitNickLength:] + 89 at FW_HomeModel.m:24, address = 0x00000001061bc169, resolved, hit count = 0

結語：

有了這些命令，調試起來肯定就得心應手了。總結下常用的，供多看幾遍加深回憶：

堆棧相關：bt查看堆棧、frame select跳幀、frame variable查看幀參數、thread return跳出當前執行、【step/finish/next/continue】進入/跳出/下一步/跳出本斷點

斷點相關：breakpoint set -f -l -c條件斷點、breakpoint set -n方法斷點、breakpoint delete斷點移除、breakpoint list斷點列表

image命令：image lookup -address崩潰定位、image lookup -name方法來源、 image lookup –type 查看成員

LLDB支持簡寫