Objective-C++ is simply source code that mixes Objective-C classes and C++ classes (two entirely unrelated entities). Your C++ code will work, just as before, and the resulting executable will be linked with the Objective-C runtime, so your Objective-C classes will work as well. You can definitely use it in Xcode -- name your files with the `.mm` extension.

Also, you might want to read [Apple&#39;s (sadly deleted, but archived) documentation on Objective-C++][1].

  [1]: https://web.archive.org/web/20101203170217/http://developer.apple.com/library/mac/#documentation/Cocoa/Conceptual/ObjectiveC/Articles/ocCPlusPlus.html &quot;The Objective-C Programming Language: Using C++ With Objective-C on Wayback Machine&quot;


Objective-C++ is Objective-C (probably with Cocoa Framework) with the ability to link with C++ code (probable classes).

Yes, you can use this language in Xcode to develop for Mac OS X, iPhone/iPodTouch, iPad. It works very well.

You don&#39;t have to do anything weird in your project to use Objective-C++. Just name your Objective-C files with the extension **.mm** (instead of **.m**) and you are good to go.

It is my favorite architecture: develop base class library of my game/application in C++ so I can reuse it in other platforms (Windows, Linux) and use Cocoa just for the iPhone/iPad **UI** specific stuff.

I&#39;m looking for a way to calculate the age of a person, given their DOB in the format dd/mm/yyyy.

I was using the following function which worked fine for several months until some kind of glitch  caused the while loop to never end and grind the entire site to a halt. Since there are almost 100,000 DOBs going through this function several times a day, it&#39;s hard to pin down what was causing this.

Does anyone have a more reliable way of calculating the age?

    //replace / with - so strtotime works
    $dob = strtotime(str_replace(&quot;/&quot;,&quot;-&quot;,$birthdayDate));		
    $tdate = time();
    	
    $age = 0;
    while( $tdate &gt; $dob = strtotime(&#39;+1 year&#39;, $dob))
    {
        ++$age;
    }
    return $age;

EDIT: this function seems to work OK some of the time, but returns &quot;40&quot; for a DOB of 14/09/1986

    return floor((time() - strtotime($birthdayDate))/31556926);

PHP calculate age

When i ssh to a machine, sometime i get this error warning and it prompts to say &quot;yes&quot; or &quot;no&quot;. This cause some trouble when running from scripts that automatically ssh to other machines.

Warning Message: 

    The authenticity of host &#39;&lt;host&gt;&#39; can&#39;t be established.
    ECDSA key fingerprint is    SHA256:TER0dEslggzS/BROmiE/s70WqcYy6bk52fs+MLTIptM.
    Are you sure you want to continue connecting (yes/no)? yes
    Warning: Permanently added &#39;pc&#39; (ECDSA) to the list of known hosts.


Is there a way to automatically say &quot;yes&quot; or ignore this?

ssh: The authenticity of host &#39;hostname&#39; can&#39;t be established

What is Objective C++ and can I use this language in Xcode?


What is Objective C++?

<p>What is Objective C++ and can I use this language in Xcode?</p>


The documentation states that: 

&gt; The Q_OBJECT macro must appear in the
&gt; private section of a class definition
&gt; that declares its own signals and
&gt; slots or that uses other services
&gt; provided by Qt&#39;s meta-object system.

But *exactly* what does that mean? On which QObject-derived classes can I safely omit it? Will problems arise if you omit Q_OBJECT on a QObject-derived class, and then inherit from that one? Basically I would like a little more information on when I can omit it from my Qt classes.

When should Q_OBJECT be used?

Is there a way to add or edit the message thrown by assert? I&#39;d like to use something like 

    assert(a == b, &quot;A must be equal to B&quot;);

Then, the compiler adds _line_, _time_ and so on...

Is it possible?

Add custom messages in assert?

What is the difference between the arguments in:

    int foo1(const Fred &amp;arg) {
    ...
    }
and

    int foo2(Fred const &amp;arg) {
    ...
    }
?
I don&#39;t see this case covered in the parashift FAQ.

C++: const reference, before vs after type-specifier

I&#39;ve just been beaten (rather hardly) on the head by some non-trivial warning from Visual Studio 2010 (C++).

The compilation gave the following output:

&gt; 1 Debug\is.obj : warning LNK4042: object specified more than once; extras ignored  
&gt; 1 Debug\make.obj : warning LNK4042: object specified more than once; extras ignored  
&gt; 1 Debug\view.obj : warning LNK4042: object specified more than once; extras ignored  
&gt; 1 identity.obj : error LNK2019: unresolved external symbol `void __cdecl
&gt; test::identity::view(void)` (?view@identity@test@@YAXXZ) referenced in function `void __cdecl test::identity::identity(void)` (?identity@0test@@YAXXZ)  
&gt; 1 identity.obj : error LNK2019: unresolved external symbol `void __cdecl test::identity::make(void)` (?make@identity@test@@YAXXZ) referenced in function `void __cdecl test::identity::identity(void)` (?identity@0test@@YAXXZ)  
&gt; 1 range.obj : error LNK2019: unresolved external symbol `void __cdecl test::range::is(void)` (?is@range@test@@YAXXZ) referenced in function `void __cdecl test::range::range(void)` (?range@0test@@YAXXZ)  

Linker errors are always a pain to debug... but there were unresolved references, and so I checked... but the source is well-formed... and finally it hit me:

My folder hierarchy looks like so:

    src/
      identity/
        is.cpp
        make.cpp
        view.cpp
      range/
        is.cpp
        make.cpp
        view.cpp

and so does the hierarchy in the Solution (I always set it up so that it mimicks the &quot;real&quot; folder structure).

And the diagnostic outputs:

    Debug\is.obj
    Debug\make.obj
    Debug\view.obj

Along with a warning which says that the `.obj` has been passed twice to the linker and that one will be ignored.

Search no more: Visual has neatly flatten my folder hierarchy, and therefore is unable to neatly compile the source.

At the moment, I am simply thinking of renaming the files, that should cover the issue...

... but is there a way to have Visual Studio NOT flatten the file hierarchy ?



Visual Studio 2010&#39;s strange &quot;warning LNK4042&quot;

I heard `auto_ptr` is being deprecated in C++11. What is the reason for this?

Also I would like to know the difference between `auto_ptr` and `shared_ptr`.

Why is auto_ptr being deprecated?

With the following snippet, I&#39;m adding a drop shadow effect to one my UIView. Which works pretty well. But as soon as I set the view&#39;s **masksToBounds** property to **YES**. The drop shadow effect isn&#39;t rendered any more.

    self.myView.layer.shadowColor = [[UIColor blackColor] CGColor];
    self.myView.layer.shadowOpacity = 1.0;
    self.myView.layer.shadowRadius = 10.0;
    self.myView.layer.shadowOffset = CGSizeMake(0.0f, 0.0f);
    self.myView.layer.cornerRadius = 5.0;
    self.myView.layer.masksToBounds = YES; // &lt;-- This is causing the Drop shadow to not be rendered
    UIBezierPath *path = [UIBezierPath bezierPathWithCurvedShadowForRect:self.myView.bounds];
    self.myView.layer.shadowPath = path.CGPath;
    self.myView.layer.shouldRasterize = YES;

Do you have any ideas on this?

Why masksToBounds = YES prevents CALayer shadow?

I have an NSString with the value of

    http://digg.com/news/business/24hr

How can I get everything before the 3rd level?

    http://digg.com/news/

Get parts of a NSURL in objective-c

How can I get the year/month/day of a `NSDate` object, given no other information? I realize that I could probably do this with something similar to this:

    NSCalendar *cal = [[NSCalendar alloc] init];
    NSDateComponents *components = [cal components:0 fromDate:date];
    int year = [components year];
    int month = [components month];
    int day = [components day];

But that seems to be a whole lot of hassle for something as simple as getting a `NSDate`&#39;s year/month/day. Is there any other solution?

NSDate get year/month/day

    - (void)someMethod
    {
        if ( [delegate respondsToSelector:@selector(operationShouldProceed)] )
        {
            if ( [delegate operationShouldProceed] )
            {
                // do something appropriate
            }
        }
    }

The [documentation][1] says:

&gt; The precaution is necessary only for optional methods in a formal protocol or methods of an informal protocol

What does it mean? If I use a formal protocol I can just use `[delegate myMethod]`?


  [1]: http://developer.apple.com/library/ios/documentation/Cocoa/Conceptual/CocoaFundamentals/CommunicatingWithObjects/CommunicateWithObjects.html#//apple_ref/doc/uid/TP40002974-CH7-SW29

when to use respondsToSelector in objective-c

Both the following comparisons evaluate to true:

1)

    @&quot;foo&quot; == @&quot;foo&quot;;

2)

    NSString *myString1 = @&quot;foo&quot;;
    NSString *myString2 = @&quot;foo&quot;;
    myString1 == myString2;

However, there are definitely times where two `NSString`s cannot be compared using the equality operator, and `[myString1 isEqualToString:myString2]` is required instead.  Can someone shed some light on this?

Understanding NSString comparison

So it&#39;s a new millennium; Apple has waved their hand; it&#39;s now legal to include a Python interpreter in an iPhone (App Store) app.

How does one go about doing this? All the existing discussion (unsurprisingly) refers to jailbreaking. (Older question: [Can I write native iPhone apps using Python][1])

[1]: https://stackoverflow.com/questions/43315/can-i-write-native-iphone-apps-using-python

My goal here isn&#39;t to write a PyObjC app, but to write a regular ObjC app that runs Python as an embedded library. The Python code will then call back to native Cocoa code. It&#39;s the &quot;control logic is Python code&quot; pattern.

Is there a guide to getting Python built in XCode, so that my iPhone app can link it? Preferably a stripped-down Python, since I won&#39;t need 90% of the standard library.

I can probably figure out the threading and Python-extension API; I&#39;ve done that on MacOS. But only using command-line compilers, not XCode.


Embedding Python in an iPhone app

I am looking at an Xcode project that uses some libraries.  The project was created on a different computer, so I need to update some paths.  The library search paths all start with `$(SRCROOT)`.  What does that mean?

Xcode -- what is $(SRCROOT)?

I&#39;d like to show the current language that the device UI is using. What code would I use? 

I want this as an `NSString` in fully spelled out format. (Not @&quot;en_US&quot;)

EDIT: For those driving on by, there are a ton of useful comments here, as the answer has evolved with new iOS releases.

Getting current device language in iOS?

I used to be able to type with my real mac keyboard after launching the iPhone Simulator. Typing with the on-screen simulator keyboard is just horrible when testing with large amounts of text.

No matter what I do, I can&#39;t get my keyboard to type anymore inside the simulator. Even if I have &quot;Simulate Hardware Keyboard&quot; switched ON, it just won&#39;t type anything. Can someone please tell me what I&#39;m doing wrong? Is there no way to type using the real keyboard anymore?

How do I type using my keyboard on the iphone simulator?

This seems like such a basic task, but I&#39;m stumped.

How, in Xcode, do you execute a textual search though (the XML contents of) all the .xib files in a project?

For example, all of our .xib files contain this string on the second line: `com.apple.InterfaceBuilder3.CocoaTouch.XIB`. So I&#39;d think that searching all project files for that string would return all .xib files, but Xcode insists &quot;0 occurrences&quot;. I&#39;ve double checked that the Project Find Options look correct.

I must be missing something obvious. (Or Xcode is somehow hard-coded to skip .xib files.)

I&#39;m trying to find all the .xib files that reference a particular class (and a text search seems like the most direct way).

Thanks!



Text search though all .xib files in Xcode?

I have an `NSString` object and want to convert it into a `std::string`.

How do I do this in Objective-C++?

How do I convert a NSString into a std::string?

A project with some Objective-C has a few C classes with the implementation files having a **.mm** extension.

    file.h
    file.mm

What does the **.mm** mean? Shouldn&#39;t it just be **.m**?


C Language: what does the .mm extension stand for?

Android with [NDK][1] has support to C/C++ code and iOS with [Objective-C++][2] has support too, so how can I write applications with native C/C++ code shared between Android and iOS?


  [1]: https://developer.android.com/ndk/index.html
  [2]: https://en.wikipedia.org/wiki/Objective-C#Objective-C.2B.2B

How to use the same C++ code for Android and iOS?

In the project I have been working on, we have to send Cocoa notifications from C++ sub-projects to the main project above it. To do this we construct a map to act as a key-value store for the userInfo dictionary of the notification.

In one of the projects, the following code compiles just fine:

    std::map&lt;std::string, std::string&gt; *userInfo = new std::map&lt;std::string, std::string&gt;;
    char buffer[255];
    
    sprintf(buffer, &quot;%i&quot;, intValue1);
    userInfo-&gt;insert(std::pair&lt;std::string, std::string&gt;(&quot;intValue1&quot;, std::string(buffer)));
    
    sprintf(buffer, &quot;%i&quot;, intValue2);
    userInfo-&gt;insert(std::pair&lt;std::string, std::string&gt;(&quot;intValue2&quot;, std::string(buffer)));
    
    if(condition)
        userInfo-&gt;insert(std::pair&lt;std::string, std::string&gt;(&quot;conditionalValue&quot;, &quot;true&quot;));
    
    PostCocoaNotification(&quot;notificationName&quot;, *userInfo);

However, when this is copied into an identical file in another sub-project, the compiler throws the following on the userInfo-&gt;insert calls:

    &quot;Implicit instantiation of undefined template &#39;std::basic_string&lt;char, std::char_traits&lt;char&gt;, std::allocator&lt;char&gt; &gt;&#39;&quot; 

..and it cannot find the function for PostCocoaNotification:

    No matching function for call to &#39;PostCocoaNotification&#39;


Additionally, it throws the following errors in system headers: 

    /Applications/Xcode.app/Contents/Developer/Platforms/iPhoneOS.platform/Developer/SDKs/iPhoneOS6.1.sdk/usr/include/c++/4.2.1/bits/stl_pair.h:73:11: Implicit instantiation of undefined template &#39;std::basic_string&lt;char, std::char_traits&lt;char&gt;, std::allocator&lt;char&gt; &gt;&#39;
    /Applications/Xcode.app/Contents/Developer/Platforms/iPhoneOS.platform/Developer/SDKs/iPhoneOS6.1.sdk/usr/include/c++/4.2.1/bits/stl_pair.h:74:11: Implicit instantiation of undefined template &#39;std::basic_string&lt;char, std::char_traits&lt;char&gt;, std::allocator&lt;char&gt; &gt;&#39;
    /Applications/Xcode.app/Contents/Developer/Platforms/iPhoneOS.platform/Developer/SDKs/iPhoneOS6.1.sdk/usr/include/c++/4.2.1/bits/stl_pair.h:73:11: Implicit instantiation of undefined template &#39;std::basic_string&lt;char, std::char_traits&lt;char&gt;, std::allocator&lt;char&gt; &gt;&#39;
    /Applications/Xcode.app/Contents/Developer/Platforms/iPhoneOS.platform/Developer/SDKs/iPhoneOS6.1.sdk/usr/include/c++/4.2.1/bits/stl_tree.h:1324:13: Cannot initialize a parameter of type &#39;_Link_type&#39; (aka &#39;_Rb_tree_node&lt;std::pair&lt;const std::basic_string&lt;char, std::char_traits&lt;char&gt;, std::allocator&lt;char&gt; &gt;, std::basic_string&lt;char, std::char_traits&lt;char&gt;, std::allocator&lt;char&gt; &gt; &gt; &gt; *&#39;) with an rvalue of type &#39;_Const_Link_type&#39; (aka &#39;const _Rb_tree_node&lt;std::pair&lt;const std::basic_string&lt;char, std::char_traits&lt;char&gt;, std::allocator&lt;char&gt; &gt;, std::basic_string&lt;char, std::char_traits&lt;char&gt;, std::allocator&lt;char&gt; &gt; &gt; &gt; *&#39;)

I&#39;ve no idea what I&#39;ve done to cause such chaos, especially when the code runs perfectly fine in another sub-project (successfully sending notifications). Any insight to the problem would be very welcome.

Content Type	Original Author	Original Content on Stackoverflow
Question	Saurabh	View Question on Stackoverflow
Solution 1 - C++	Doches	View Answer on Stackoverflow
Solution 2 - C++	Pablo Santa Cruz	View Answer on Stackoverflow

What is Objective C++?

C++ Problem Overview

C++ Solutions

Solution 1 - C++

Solution 2 - C++

ssh: The authenticity of host 'hostname' can't be established

PHP calculate age

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