iphone workshop

8/6/2019 iPhone workshop

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Objectives

Learn Debug Mode and Release ModeLearn Debug Mode and Release Mode

Learn LogLearn Log

Learn DebugLearn Debug iPhoneiPhone ApplicationApplication


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Outcome

Understand how to debuggingUnderstand how to debugging iPhoneiPhone

application.application.


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Debugging for iPhone

application

In the development ofIn the development of applications,applications, youyou

oftenoften encounterencounter the followingthe following problems: Syntaxproblems: Syntax

Error, Execution Error (e.g. unexpected resultsError, Execution Error (e.g. unexpected results

came out, system stopped execution, etc.).came out, system stopped execution, etc.).

WeWe explainexplain howhow to outputto output the log informationthe log information andand

debuggingdebugging iPhoneiPhone application.application.


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Debug Mode and

Release Mode

YouYou cancan select the format of the Buildselect the format of the Build code:code:

iPhoneiPhone DeviceDevice oror Simulator.Simulator.

iPhoneiPhone // iPadiPad cancan connectconnect via USBvia USB to theto the MacMac

machine.machine.

YouYou cancan testtest your application onyour application on youryour iPhoneiPhone

devicedevice


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Debug Mode and

Release Mode

Figure 5Figure 5--1,1, in thein the development process,development process,

youyou cancan select the format of the Buildselect the format of the Build code:code:


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Debug Mode and

Release Mode

In selectingIn selecting iPhoneiPhone or Simulator, theor Simulator, the

mainmain difference is thatdifference is that the resources onthe resources on iPhoneiPhone

are less than the Simulator (such as the CPU isare less than the Simulator (such as the CPU is

not so fast and the memory is not sufficient).not so fast and the memory is not sufficient).

You must eventually test the application onYou must eventually test the application on

iPhoneiPhone device to see if the speed is acceptable.device to see if the speed is acceptable.


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Build mode

Choose between two output modes, i.e. Debug andChoose between two output modes, i.e. Debug andRelease.Release.

Debug modeDebug mode -- moremore debugging information.debugging information.

Release modeRelease mode -- faster andfaster and more optimized.more optimized.

When you deploy your application to theWhen you deploy your application to theusers,users, youyou need to select Release mode.need to select Release mode.

Developers are generally using Debug mode.Developers are generally using Debug mode.


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Build mode

FigureFigure 55--2, after build, the build contents are put2, after build, the build contents are put

under the build folder.under the build folder.


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Log

WeWe often need tooften need to outputoutput aa loglog message.message.

LogLog is oftenis often divided intodivided into multiple levels, e.g.:multiple levels, e.g.:

onlyonly outputoutput error messageserror messages

output debug informationoutput debug information

UseUse NSLogNSLog method tomethod to loglog information.information.


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Log

IfIf you do not knowyou do not know NSLogNSLog method,method, then you canthen you can

highlighthighlight NSLogNSLog and rightand right--clickclick

In theIn the popup menu, selectspopup menu, selects "Find Text in"Find Text in

Documentation (see Figure 5Documentation (see Figure 5--3)3)

You will get the usage information of thatYou will get the usage information of that

method.method.


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Log

Find Text in Documentation (Figure 5Find Text in Documentation (Figure 5--3)3)


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Log

As shownAs shown in Figurein Figure 55--4,4, wewe will demonstratewill demonstrate howhow

to addto add and view the log.and view the log.


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Log

FigureFigure 55--44 -- Definition ofDefinition of NSLogNSLog


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Log

UnderUnder changeNumberchangeNumber method, add anmethod, add an NSLogNSLog

method to output some remind messages.method to output some remind messages.

- (IBAction) changeNumber: (id) sender

{int sliderValue = slider.value;

number.text = [NSString stringWithFormat: @ "% d", sliderValue];NSLog (@ "This is changeNumber method");

}


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Log

Save andSave and run the program,run the program, movemove the sliderthe slider

several times.several times.

SingleSingle--click "gab"click "gab" buttonbutton (the(the

rightmostrightmost blackblack button) tobutton) to open theopen the DebuggerDebugger

Console.Console.

Log messageLog message is displayed in theis displayed in the debuggerdebugger

consoleconsole


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Log

[5[5--5] Open Debugger Console5] Open Debugger Console


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Log

[5[5--6] Debugger Console6] Debugger Console


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Log

Debugger ConsoleDebugger Console also showsalso shows system message.system message.

For example, if your application stoppedFor example, if your application stopped

execution due to some exceptions, then you mayexecution due to some exceptions, then you may

want to check the information here.want to check the information here.


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Debug iPhone Application

SupposeSuppose the followingthe following program,program, sliderValuesliderValue waswas

written wrongly as written wrongly as slideValueslideValue

- (IBAction) changeNumber: (id) sender

{

int sliderValue = slider.value;number.text = [NSString stringWithFormat: @ "% d", slideValue];/ / Originally sliderValue at the end

NSLog (@ "This is changeNumber method");

}


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when youwhen you click "Build and Run", youclick "Build and Run", you will seewill see

thethe error message:error message:

"" ''slideValueslideValue' undeclared' undeclared ""


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[5[5--7] Build error7] Build error


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Under the window, on the left, it shows an error and aUnder the window, on the left, it shows an error and awarning.warning.

The right also shows the same message.The right also shows the same message.

DoubleDouble--click the small red icon, it will open Buildclick the small red icon, it will open BuildResult windowResult window

The window displays the error and warning message.The window displays the error and warning message.


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[5[5--8] Build Result Windows8] Build Result Windows


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Breakpoint Debug

Set a breakpoint on a line of the program.Set a breakpoint on a line of the program.

When you debug a program, the system will pause onWhen you debug a program, the system will pause on

this line.this line.

At this point, you can check a lot of information, suchAt this point, you can check a lot of information, suchas whether the value of the variable is as expected.as whether the value of the variable is as expected.

You can always set a breakpoint in any line that youYou can always set a breakpoint in any line that you

suspect it may contain error.suspect it may contain error.


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Breakpoint Debug

You can set a breakpoint in the first line of yourYou can set a breakpoint in the first line of your

program and select line by line executionprogram and select line by line execution

The program will be executed line by line.The program will be executed line by line.

Here, we demonstrate how to use breakpointHere, we demonstrate how to use breakpointdebugging function.debugging function.


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Breakpoint Debug Set

Breakpoint

On the left side of the code, click the line whereOn the left side of the code, click the line where

you want to set a breakpoint.you want to set a breakpoint.

Then, you will see a small blue arrow is added.Then, you will see a small blue arrow is added.

At the same time, the button in the tool bar,At the same time, the button in the tool bar,Build and Run becomes Build and Debug.Build and Run becomes Build and Debug.


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Breakpoint

[5[5--9] Set Breakpoint9] Set Breakpoint


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Breakpoint

SingleSingle--click "Build and Debug" button to debug.click "Build and Debug" button to debug.

Firstly, the system will display a normalFirstly, the system will display a normal iPhoneiPhone

window.window.

Moving the slider, the system jumps to the lineMoving the slider, the system jumps to the linewhere you set the breakpoint.where you set the breakpoint.


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Breakpoint

[5[5--10] application startup10] application startup


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Breakpoint

[5[5--11] to the Breakpoint execution11] to the Breakpoint execution


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Breakpoint Debug

On the left side of gab button, singleOn the left side of gab button, single--click Showclick ShowDebugger button (yellow button).Debugger button (yellow button).

Then, it will open a debugger windowThen, it will open a debugger window

You can also click Run from the menu to startYou can also click Run from the menu to startdebugger windows.debugger windows.


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Breakpoint Debug -

Debugger windows

When you move the mouse to each variable, the codeWhen you move the mouse to each variable, the codebelow will display the current value of the variablebelow will display the current value of the variable

In column of the "Build and Debug" button, you willIn column of the "Build and Debug" button, you will

see all debug buttons which are similar to most ofsee all debug buttons which are similar to most of

the debugging tools.the debugging tools.


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Breakpoint Debug -

Debugger windows

Step Over: Executes the next line of code, if theStep Over: Executes the next line of code, if thecurrent line is a method call, it will not enter thecurrent line is a method call, it will not enter theinternal methods.internal methods.

Step Into: Enter the methodStep Into: Enter the method

Step Out: Skip the current method and executes toStep Out: Skip the current method and executes tothe end of the current methodthe end of the current method

Continue: Continue executing the current code. IfContinue: Continue executing the current code. Ifthere is the next breakpoint, then it will stop at thethere is the next breakpoint, then it will stop at thenext breakpoint.next breakpoint.


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Breakpoint Debug -

Debugger windows

[5[5--13] Display values of variable13] Display values of variable


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Breakpoint Debug -

Debugger windows

Finally, you singleFinally, you single--click "Continue" button toclick "Continue" button tocontinue executing the application.continue executing the application.

If you want to get rid of breakpoint, you canIf you want to get rid of breakpoint, you can

rightright--click the breakpoint, from the popclick the breakpoint, from the pop--upup

menu, select "Remove Breakpoint".menu, select "Remove Breakpoint".


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Breakpoint Debug -

Debugger windows

[5[5--14] Remove breakpoint14] Remove breakpoint


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Try it out now

Please also finish the exercisePlease also finish the exercise


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End

iphone workshop

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