iOS Simulator screen shots are saved to your desktop (`~/Desktop`).  The file names are of the form `iOS Simulator Screen shot Feb 28, 2012 12.16.23 PM.png`.

You can also choose Edit &gt; Copy Screen (default shortcut: &lt;kbd&gt;⌃⌘C&lt;/kbd&gt;) to copy the screen shot directly to your clipboard.


Press Command+S. The screen shot will be saved on your desktop.

On iOS 9.3, the screen shots are called `Simulator Screen Shot &lt;timestamp&gt;.png` and are still located in `~/Desktop`.

For newcomers, let&#39;s just use Xcode &quot;Debug&quot; option in the Menu:

Debug -&gt; View Debugging -&gt; Take screenshot of yourPhoneName
-----------------------------------------------------------
(see image below)

The screenshots are saved on the Desktop. I tried only for phone connected to my computer, but it should work also on simulators.  

[![enter image description here][1]][1]


  [1]: https://i.stack.imgur.com/yS8HJ.png

For Xamarin developers using remote MAC pairing from windows, the screenshots are located in Pictures &gt; Xamarin &gt; iOS Simulator directory.

I need to sort a PostgreSQL table ascending by a date/time field, e.g. `last_updated`.

But that field is allowed to be empty or null and I want records with null in `last_updated` come *before* non-null `last_updated`.  
Is this possible?

    order by last_updated asc  -- and null last_updated records first ??

Sort by column ASC, but NULL values first?

&gt; **Possible Duplicate:**  
&gt; [Why doesn&amp;#39;t GCC optimize structs?](https://stackoverflow.com/questions/118068/why-doesnt-gcc-optimize-structs)  
&gt; [Why doesn&amp;#39;t C++ make the structure tighter?](https://stackoverflow.com/questions/6730664/why-doesnt-c-make-the-structure-tighter)  

&lt;!-- End of automatically inserted text --&gt;

Consider the following example on a 32 bit x86 machine:

Due to alignment constraints, the following struct

    struct s1 {
        char a;
        int b;
        char c;
        char d;
        char e;
    }

could be represented more memory-efficiently (12 vs. 8 bytes) if the members were reordered as in

    struct s2 {
        int b;
        char a;
        char c;
        char d;
        char e;
    }

I know that C/C++ compilers are not allowed to do this. My question is why the language was designed this way. After all, we may end up wasting vast amounts of memory, and references such as `struct_ref-&gt;b` would not care about the difference.



**EDIT**: Thank you all for your extremely useful answers. You explain very well why rearranging doesn&#39;t work because of the way the language was designed. However, it makes me think: Would these arguments would still hold if rearrangement was part of the language? Let&#39;s say that there was some specified rearrangement rule, from which we required at least that

 1. we should only reorganize the struct if actually necessary (don&#39;t do anything if the struct is already &quot;tight&quot;)
 2. the rule only looks at the definition of the struct, not inside inner structs. This ensures that a struct type has the same layout whether or not it is internal in another structure
 3. the compiled memory layout of a given struct is predictable given its definition (that is, the rule is fixed)

Adressing your arguments one by one I reason:

*  _Low-level data mapping, &quot;element of least surprise&quot;_: Just write your structs in a tight style yourself (like in @Perry&#39;s answer) and nothing has changed (requirement 1). If, for some weird reason, you want internal padding to be there, you could insert it manually using dummy variables, and/or there could be keywords/directives.

*  _Compiler differences_: Requirement 3 eliminates this concern. Actually, from @David Heffernan&#39;s comments, it seems that we have this problem today because different compilers pad differently?

*  _Optimization_: The whole point of reordering is (memory) optimization. I see lots of potential here. We may not be able to remove padding all together, but I don&#39;t see how reordering could limit optimization in any way.

*  _Type casting_: It seems to me that this is the biggest problem. Still, there should be ways around this. Since the rules are fixed in the language, the compiler is able to figure out how the members were reordered, and react accordingly. As mentioned above, it will always be possible to prevent reordering in the cases where you want complete control. Also, requirement 2 ensures that type-safe code will never break.

The reason I think such a rule could make sense is because I find it more natural to group struct members by their contents than by their types. Also it is easier for the compiler to choose the best ordering than it is for me when I have a lot of inner structs. The optimal layout may even be one that I cannot express in a type-safe way. On the other hand, it would appear to make the language more complicated, which is of course a drawback.

Note that I am not talking about changing the language - only if it could(/should) have been designed differently.

I know my question is hypothetical, but I think the discussion provides deeper insight in the lower levels of the machine and language design.

I&#39;m quite new here, so I don&#39;t know if I should spawn a new question for this. Please tell me if this is the case.

Why can&#39;t C compilers rearrange struct members to eliminate alignment padding?

I can&#39;t find iOS simulator screenshots (supposedly created using &lt;kbd&gt;cmd&lt;/kbd&gt;+&lt;kbd&gt;S&lt;/kbd&gt;) since updating to Xcode 4.3 (running on 10.7.3 Lion).

They aren&#39;t in `~Library/Application Support/Developer/Shared/Xcode/Screenshots`.

Presumably they moved when Xcode moved from `Developer`, but Spotlight can&#39;t tell me where they are either.



Where does the iOS Simulator save screen shots?

I can't find iOS simulator screenshots (supposedly created using <kbd>cmd</kbd>+<kbd>S</kbd>) since updating to Xcode 4.3 (running on 10.7.3 Lion).
They aren't in <code>~Library/Application Support/Developer/Shared/Xcode/Screenshots</code>.
Presumably they moved when Xcode moved from <code>Developer</code>, but Spotlight can't tell me where they are either.

I&#39;m trying to make my project compatible with Snow Leopard and I am not able to remove the autolayout in the nibs using Interface builder (XCode 4.3 on Lion).

Is it possible to remove the constraints and the autolayout in a nib on XCode?

Remove autolayout (constraints) in Interface Builder

I get the following error messages when I moved my code from my laptop to my Mac Mini and opened it over there:


&gt;myProject is locked for editing and you may not be able to save your changes?

---

&gt;myProject is currently locked because you are not the owner of the file and do not have write permission.

---------------

&gt;The file &quot;xxx.xcuserdatad&quot; could not be unlocked.
Could not add write permission to the file because you do not own it.  Try modifying the permission of the file in the Finder or Terminal.

---------------

I did a search with Finder:  What came up was a file called UserInterfaceState.xcuserstate inside of xxx.xcuserdatad... GetInfo showed the file not to be locked. 

However looking at the path(from GetInfo) showed the file to be within &quot;xxx.xcodeproj&quot; and further within &quot;project.xcworkspace/xcuserdata/xxx.xcuserdatad&quot;

I can&#39;t find this anywhere, and I don&#39;t know how to use my project on another computer.

myProject is locked for editing and you may not be able to save your changes?

Is it possible to segue from one storyboard to another, or to embed a storyboard in a view controller in another storyboard? I need to place a `UITabBarController` in a `UINavigationController`, and I&#39;d like to keep them nice and separate.

Segue to another storyboard?

Can someone explain what do these options in Xcode do?

* Enable Scribble
* Enable Guard Edges
* Enable Guard Malloc

what they are and what they do and how useful can they be for debugging/testing?

thanks.

Xcode - scribble, guard edges and guard malloc

OMG, what I&#39;ve done? 

Couple of days ago, I tried using macport to install something, because I&#39;m using Xcode 4.3 and the command-line tool hadn&#39;t been installed by the time, macport wouldn&#39;t work. So I followed some guide to get command-line tool installed, then I used following command:

    sudo xcode-select -switch /Applications/Xcode.app/

which I think screwed everything except macport: now, in Xcode, even a simple single-view iOS project won&#39;t be compiled, it says &quot;UIKit/UIKit.h not found&quot;.

Does anyone know how to correct this? I don&#39;t want to re-install the gigantic Xcode again, gotta do some iOS project tonight, help!

Xcode stops working after set &quot;xcode-select -switch&quot;

How to simulator the action of &quot;press the home button&quot;?

Why there is no &quot;Home&quot; button in iPad simulator in iOS 5.1 SDK?

when i compile my app, Xcode just says &quot;Attaching to Projectname...&quot; and gets stuck there.
The debugger just prints this out:
&gt; error: failed to attach to process ID 0

I tried to clean &amp; build again and it still doesn&#39;t work out. I googled but couldn&#39;t find anything helpful.
How can I fix this problem? Thank You!

Xcode compiles my App, but can&#39;t run it in the simulator

I&#39;m trying some iOS test applications on the new Mac mini, that supports Bluetooth Low Energy. The [CoreBluetooth][1] framework is used in those. However, I&#39;m not able to get Bluetooth working in the iPhone simulator, that is part of Xcode.

When I allocate a new [CBCentralManager][2], centralManagerDidUpdateState: receives `CBCentralManagerStatePoweredOff` which stands for *Bluetooth is currently powered off.*

The first time I ran the text application, a box was then opened up that looked pretty bugged (only language variables were used, not the actual texts) and with two buttons. The first led me to the settings panel where there was an option to enable Bluetooth. However, after I told it to enable Bluetooth, it just shows the spinning animation, and it won&#39;t either complete or cancel. Even after rebooting the Mac, there is still only the spinning animation. The box also does not open up anymore.

Essentially, I think that the iPhone simulator should support Bluetooth Low Energy. Otherwise, it does not really make sense that there is an option in the settings application on the simulator. Also, the central manager state is `CBCentralManagerStatePoweredOff` but not `CBCentralManagerStateUnsupported` which would stand for *The platform doesn&#39;t support Bluetooth Low Energy*. This gives also hope that support could exist.

- Does the iPhone simulator support Bluetooth Low Energy?
- If yes, how can I enable it?


  [1]: http://developer.apple.com/library/ios/#documentation/CoreBluetooth/Reference/CoreBluetooth_Framework/_index.html
  [2]: http://developer.apple.com/library/ios/#documentation/CoreBluetooth/Reference/CBCentralManager_Class/translated_content/CBCentralManager.html

Does the iPhone simulator in Xcode support Bluetooth Low Energy?

I want to see what happens in the iOS Simulator if I&#39;m not testing the app in Xcode.

For example, if I open a link in the Safari simulator, see what happens in the console,
or if I install a web-app, see the links that I&#39;m pressing in console.

How can I do this?

I want to see it in Xcode or Terminal, but it&#39;s not a problem if I need to use another bit of software.

How can I get the console logs from the iOS Simulator?

On my old Mac running Snow Leopard, I could type &quot;ios&quot; into spotlight and it would start up the iPhone/iPad emulator by itself.

I have since had to get a new machine running Lion. I have installed Xcode for Lion, I have installed the developer tool options from the preferences panel.

But the &quot;ios&quot; option is no longer there :(  The only way now seems to be to run Xcode, create an empty project and then launch emulator with the run option.

I have searched and searched the intertubes and the facewebs, but nothing helps.

Does anyone know how to run only the emulator on Lion?

UPDATE:
THIS IS RESPONSE TO @ike_love thread below.
THAT answer is not assured to work on all Yosemite machines.

[![enter image description here][1]][1]


  [1]: http://i.stack.imgur.com/mtMeC.png

Content Type	Original Author	Original Content on Stackoverflow
Question	Snips	View Question on Stackoverflow
Solution 1 - Xcode	rob mayoff	View Answer on Stackoverflow
Solution 2 - Xcode	Saad Ur Rehman	View Answer on Stackoverflow
Solution 3 - Xcode	Pelle Stenild Coltau	View Answer on Stackoverflow
Solution 4 - Xcode	Edess Elder	View Answer on Stackoverflow
Solution 5 - Xcode	chaosifier	View Answer on Stackoverflow

Where does the iOS Simulator save screen shots?

Xcode Problem Overview

Xcode Solutions

Solution 1 - Xcode

Solution 2 - Xcode

Solution 3 - Xcode

Solution 4 - Xcode

Debug -> View Debugging -> Take screenshot of yourPhoneName

Solution 5 - Xcode

Why can't C compilers rearrange struct members to eliminate alignment padding?

Sort by column ASC, but NULL values first?

Attributions