Advanced iOS Debugging (Reloaded)

The debug process constitutes an important part in an app's development cycle. Knowing the (right) tools and techniques means you can optimizes time and therefore costs. In this session we will see a number of techniques to optimize debugging of iOS applications exploiting the power of Xcode, LLDB and other support tools.

Transcript

1. Advanced iOS Debugging Massimo Oliviero
2. Massimo Oliviero Freelance Software Developer web http://www.massimooliviero.net email massimo.oliviero@gmail.com slide http://www.slideshare.net/MassimoOliviero twitter @maxoly
3. Massimo Oliviero http://pragmamark.org/ La prima community di sviluppatori iOS e Mac OS X in Italia. https://www.facebook.com/groups/pragmamark/
4. Agenda ‣ Code, some tips for standard functions ‣ Xcode, the best tools for debugging ‣ LLDB, your great friend ‣ Tools, network debugging how to and more ‣ Remote, over the air debugging ‣ Resources, links and videos
5. Source code Kimera A simple iOS application for educational purpose https://github.com/maxoly/Kimera
6. Code
7. It all began... NSLog(@"Error :( %@", error); NSLog(@"User: %@", user); NSLog(@"Array: %@", array); NSLog(@"URL: %@", url); NSLog(@"Count: %i", count); NSLog(@"User %@", user); NSLog(@"Array %@", array); NSLog(@"Error :( %@", error); NSLog(@"Error :( %@", error NSLog(@"URL: %@", url); NSLog(@"Array: %@", array); NSLog(@"User: NSLog(@"User: %@", user); NSLog(@"User: %@", user); NSLog(@"User: %@", user); NSLog(@"User: %@", user); NSLog(@"User: %@", user); NSLog(@"User: %@", user);
8. NSLog ‣ It prints debugs output only to the console ‣ It’s a simple native Foundation function ‣ It’s not too bad, but It’s an ancient technique ‣ It slows things down considerably (if not handled)
9. NSLog optimization ‣ Use convenient macro ‣ Use string conversion functions ‣ Try alternative frameworks
10. #if defined DEBUG #define MYNSLog(s, ...) NSLog((@"%s [Line %d] " s), __PRETTY_FUNCTION__, __LINE__, ##__VA_ARGS__) #else #define MYNSLog(s, ...) #endif -[TestViewController viewDidLoad] [Line 33] message - (void)viewDidLoad { [super viewDidLoad]; MYNSLog(@"message"); } MyGreatApp-prefix.pch TestViewController.m Console NSLog macro
11. NSLog macro ‣ Enables DEBUG mode output only ‣ Outputs function name and line number ‣ Place macro into .pch le or in a header le ‣ You can use other macros like __ FILE__ (for example)
12. CGPoint point = CGPointMake(10.5f, 12.3f); NSLog(@"point: %@", NSStringFromCGPoint(point)); AdvanceDebuggingExample[3050:c07] point: {10.5, 12.3} AdvanceDebuggingExample.m Console String conversion functions
13. String conversion functions ‣ NSStringFromCGAffineTransform ‣ NSStringFromCGPoint ‣ NSStringFromCGRect ‣ NSStringFromCGSize ‣ NSStringFromUIEdgeInsets ‣ NSStringFromUIOffset
14. Try alternative framworks ‣ CocoaLumberjack https://github.com/robbiehanson/CocoaLumberjack ‣ NSLogger https://github.com/fpillet/NSLogger ‣ DMLogger https://github.com/malcommac/DMLogger
15. Demo
16. Xcode
17. Xcode ‣ Con gure your Behaviors ‣ Print more information with Arguments ‣ Push the limit with Build Settings ‣ Go beyond logging with Breakpoints
18. Behaviors
19. Xcode default Debugger bar
20. Xcode default Behaviors Variables View Console Debugger Navigator
21. Xcode Behaviors ‣ Match Xcode to your Work ow ‣ Use Behaviors to control Xcode ‣ Behaviors lets you specify what should happen when a variety of events occur (like Run)
22. Behaviors When pauses Show Debug Navigator Show debugger views
23. Change default Behavior For example, when Running pauses: ‣ show the Breakpoint Navigator instead of Debug Navigator ‣ show only Variable Views ‣ open another tab only with Console view
24. Demo
25. Arguments
26. Arguments Product > Scheme > Edit Scheme > Arguments
27. Core Data Logging -com.apple.CoreData.SQLDebug 1
28. Core Data and iCloud logging -com.apple.coredata.ubiquity.logLevel 3
29. Build Settings
30. Enable Static Analyzer
31. Treat Warning as Error
32. Warnings
33. Warnings - Objective-C
34. Breakpoints
35. Creating and editing breakpoint
36. Breakpoint Navigator
37. Exception Breakpoint
38. Symbolic Breakpoint
39. Breakpoint Action
40. Breakpoint Action Condition to evaluate The num of time to ignore breakpoint before stoping Log Message Action Debugger Command Action Play sound Continue program execution
41. Debugger Command Action po variable expr (void)NSLog(@”variable: %@”, variable) breakpoint set -f ADEMasterViewController.m -l 83
42. Sharing Breakpoint Share breakpoints with the team, so that all can bene t from it This action will create a new directory to be committed in the repository AdvanceDebuggingExample.xcodeproj/xcshareddata/
43. Demo
44. LLDB
45. Why LLDB ‣ Consistent Command Syntax ‣ Scriptability with Python ‣ Performance ‣ ...
46. LLDB Commands print object po [object] print variable print [variable] assign value expr [variable] = [value] (lldb) <command>
47. LLDB Commands set breakpoint breakpoint set -f [file] -l [line] load script command script import ~/test.py evaluate expression expr <expression> <noun> <verb> [-options [option-value]] [argument [argument...]]
48. Custom Object, the problem No summary for custom object @interface KMRMArgument : NSObject @property (nonatomic, strong) NSString *name; @property (nonatomic, strong) NSDate *detail; @end KMRMArgument *argument = [[KMRMArgument alloc] init]; argument.title = @"Debugging"; argument.when = @"Some advance techniques"; Init object Custom object
49. Custom Summary, the solution ‣ Create a Python script that will instruct LLDB on how to display a summary of your custom object ‣ Load your Python script via command line or ~/.lldbinit le
50. Custom Summary ‣ Create “KMRMArgument_summary.py” in Xcode project ‣ Then load script: (lldb) command script import /path/to/KMRMArgument_summary.py import lldb def arg_summary(valobj, internal_dict): ! nameAsString = valobj.GetChildMemberWithName('_name').GetSummary() ! detailAsString = valobj.GetChildMemberWithName('_detail').GetSummary() ! return 'Title: ' + nameAsString + ' - detail: ' + detailAsString def __lldb_init_module(debugger, dict): debugger.HandleCommand('type summary add KRMRArgument -F KRMRArgument_summary.arg_summary')
51. Console tips (lldb) po [self.view recursiveDescription] $7 = 0x082a2c60 <UITableView: 0x8971000; frame = (0 0; 320 504); clipsToBounds = YES; autoresize = W+H; gestureRecognizers = <NSArray: 0x8184be0>; layer = <CALayer: 0x8184570>; contentOffset: {0, 0}> | <UITableViewCell: 0x8282900; frame = (0 176; 320 44); text = '2013-03-12 21:22:34 +0000'; autoresize = W; layer = <CALayer: 0x8282a30>> | | <UITableViewCellContentView: 0x8282a60; frame = (0 0; 300 43); gestureRecognizers = <NSArray: 0x8282c30>; layer = <CALayer: 0x8282ac0>> | | | <UILabel: 0x8282e50; frame = (10 0; 280 43); text = '2013-03-12 21:22:34 +0000'; clipsToBounds = YES; userInteractionEnabled = NO; layer = <CALayer: 0x8282ee0>> | | <UIButton: 0x8282c80; frame = (290 0; 30 43); opaque = NO; userInteractionEnabled = NO; layer = ... (lldb) po [[UIWindow keyWindow] recursiveDescription] $5 = 0x08273bc0 <UIWindow: 0x8181010; frame = (0 0; 320 568); layer = <UIWindowLayer: 0x81810e0>> | <UILayoutContainerView: 0xd06eed0; frame = (0 0; 320 568); autoresize = W+H; layer = <CALayer: 0xd071460>> | | <UINavigationTransitionView: 0xd09e850; frame = (0 0; 320 568); clipsToBounds = YES; autoresize = W +H; layer = <CALayer: 0xd09e920>> | | | <UIViewControllerWrapperView: 0x846e160; frame = (0 64; 320 504); autoresize = W+H; layer = <CALayer: 0x846e210>> ...
52. Demo
53. Tools
54. Tools ‣ Network Link Conditioner ‣ Charles ‣ PonyDebugger ‣ Deploymate ‣ Spark Inspector
55. Network Link Conditioner
56. Network Link Conditioner ‣ It’s a utility that enables you to simulate network conditions ‣ To install just select Xcode > Open Developer Tool > More Developer Tools. You’ll be taken to Apple’s developer downloads site ‣ Download “Hardware IO Tools for Xcode”
57. Network Link Conditioner
58. Charles
59. Charles Proxy ‣ It’s a web debugging proxy ‣ You can inspect, modify and record requests & responses ‣ SSL Proxing http://www.charlesproxy.com/documentation/faqs/ssl-connections- from-within-iphone-applications/ ‣ http://www.charlesproxy.com ‣ Price start from US$50
60. Charles Proxy
61. PonyDebugger
62. PonyDebugger ‣ Network Traffic Debugger ‣ Core Data Browser ‣ It is a client library and gateway server combination that uses Chrome Developer Tools on your browser to debug your application's network traffic and managed object contexts. ‣ https://github.com/square/PonyDebugger
63. PonyDebugger
64. Deploymate
65. Deploymate ‣ If using an API introduced later than your target OS but your app is targeting an older OS version, Xcode doesn't warn you about it ‣ It helps identify unavailable, deprecated and obsolete API ‣ http://www.deploymateapp.com/ ‣ Price US$19.99
66. Deploymate
67. Spark Inspector
68. Spark Inspector ‣ Runtime Debugger for iOS ‣ Monitor & Experiment in Real-time ‣ See Noti cations in Real-time ‣ http://sparkinspector.com/ ‣ Price € 31,79
69. Spark Inspector
70. Demo
71. Remote
72. Remote debugging ‣ Apple Crash Reports ‣ PLCrashReporter ‣ TestFlight
73. Apple Crash Reports
74. Apple Crash Reports ‣ For app published on App Store, you can acquire crash log from iTunes Connect and import it into Organizer for symbolication ‣ To symbolicate a crash log, Xcode needs to have access to the matching application binary that was uploaded to the App Store, and the .dSYM le that was generated when that binary was built. This must be an exact match ‣ https://itunesconnect.apple.com
75. Apple Crash Reports
76. Apple Crash Reports
77. Xcode Symbolication
78. PLCrashReporter
79. PLCrashReporter ‣ In-process CrashReporter framework for the iPhone and Mac OS X ‣ Handles both uncaught Objective-C exceptions and fatal signals ‣ Backtraces for all active threads are provided ‣ https://code.google.com/p/plcrashreporter/
80. PLCrashReporter - (void) handleCrashReport { PLCrashReporter *crashReporter = [PLCrashReporter sharedReporter]; NSData *crashData; NSError *error; // Try loading the crash report crashData = [crashReporter loadPendingCrashReportDataAndReturnError: &error]; if (crashData == nil) { NSLog(@"Could not load crash report: %@", error); goto finish; } PLCrashReport *report = [[[PLCrashReport alloc] initWithData: crashData error: &error] autorelease]; if (report == nil) { NSLog(@"Could not parse crash report"); goto finish; } .... return; } // from UIApplicationDelegate protocol - (void) applicationDidFinishLaunching: (UIApplication *) application { PLCrashReporter *crashReporter = [PLCrashReporter sharedReporter]; NSError *error; // Check if we previously crashed if ([crashReporter hasPendingCrashReport]) [self handleCrashReport]; // Enable the Crash Reporter if (![crashReporter enableCrashReporterAndReturnError: &error]) NSLog(@"Warning: Could not enable crash reporter: %@", error); }
81. TestFlight
82. TestFlight ‣ Invite your testers, drop in the SDK and start uploading your builds. ‣ Upload your builds and TestFlight takes care of the rest. Painless over-the-air distribution to your testers and distribution lists. ‣ Complete tracking of your build, from distribution to sessions, checkpoints and crashes. ‣ https://test ightapp.com
83. TestFlight Apps Management
84. TestFlight Crashes
85. Resources
86. Resources ‣ Links ‣ Videos
87. Links
88. Links ‣ Overview of iOS Crash Reporting Tools http://www.raywenderlich.com/33669/overview-of-ios-crash- reporting-tools-part-1 http://www.raywenderlich.com/33669/overview-of-ios-crash- reporting-tools-part-2 ‣ How to use Instruments in Xcode http://www.raywenderlich.com/23037/how-to-use-instruments-in- xcode ‣ Demystifying iOS Application Crash Log http://www.raywenderlich.com/23704/demystifying-ios-application- crash-logs
89. Links ‣ Intermediate Debugging with Xcode 4.5 http://www.raywenderlich.com/28289/debugging-ios-apps-in- xcode-4-5 ‣ Xcode LLDB Tutorial http://www.cimgf.com/2012/12/13/xcode-lldb-tutorial/ ‣ iOS Simulator Tips & Tricks http://mobile.tutsplus.com/tutorials/iphone/ios-simulator/
90. Links ‣ Compiler Warnings for Objective-C Developers http://oleb.net/blog/2013/04/compiler-warnings-for-objective-c- developers/ ‣ Defensive Programming in Cocoa http://www.mikeash.com/pyblog/friday-qa-2010-08-27-defensive- programming-in-cocoa.html ‣ Testing and Debugging in iOS Simulator https://developer.apple.com/library/ios/#documentation/IDEs/ Conceptual/iOS_Simulator_Guide/TestingontheiOSSimulator/ TestingontheiOSSimulator.html
91. Links ‣ iOS Debugging (slide by Dave Kozol) http://arbormoon.com/sites/default/ les/ ASIDebuggingCocoaConfChicago.pdf ‣ Strong, Better, Faster with Instruments and Debugging (slide by Kyle Richter) http://dragonforged.com/CocoaConf.pdf ‣ LLDB Script Examples http://llvm.org/svn/llvm-project/lldb/trunk/examples/
92. Videos
93. Videos ‣ WWDC 2012 - 415 - Debugging with LLDB ‣ WWDC 2011 - 321 - Migrating from GDB to LLDB ‣ WWDC 2010 - 316 - Debugging with Xcode 4 and LLDB ‣ NSScreenCast - 002 - Memory Problems
94. Final Thoughts
95. Final Thoughts ‣ Don’t use NSLog anymore ;) ‣ Create your Xcode Behaviors ‣ Breakpoints are your friends ‣ LLDB is a promising youngster ‣ Tools can save your life ‣ The QA phase is essential
96. Thank you Massimo Oliviero massimo.oliviero@gmail.com http://www.massimooliviero.net follow me on twitter @maxoly http://www.slideshare.net/MassimoOliviero https://speakerdeck.com/massimooliviero