Advanced iOS Debugging (Reloaded)

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.

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Massimo Oliviero

July 18, 2013
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  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