An &#39;atomic write&#39; is one where you are guaranteed to have either a correct, complete write to the file or an error. There&#39;s no chance that, say, half of the write will work and then something bad happens (lost power, drive crash, etc) and the rest of the write fails. It&#39;s all or nothing. This is generally what you want.

atomically

If YES, the data is written to a backup file, and then—assuming no errors occur—the backup file is renamed to the name specified by path; otherwise, the data is written directly to path.

I trying to write a query (with subquery) but i don&#39;t know how set a limit in my subquery.
My query:

  

    $query_ids = $this-&gt;getEntityManager()
          -&gt;createQuery(
            &quot;SELECT e_.id
            FROM MuzichCoreBundle:Element e_
            WHERE [...]
            GROUP BY e_.id&quot;)
         -&gt;setMaxResults(5)
        ;

    $query_select = &quot;SELECT e
          FROM MuzichCoreBundle:Element e 
          WHERE e.id IN (&quot;.$query_ids-&gt;getDql().&quot;)
          ORDER BY e.created DESC, e.name DESC&quot;
        ;

    $query = $this-&gt;getEntityManager()
          -&gt;createQuery($query_select)
          -&gt;setParameters($params)
        ;

But **-&gt;setMaxResults(5)** doesn&#39;t work. No &#39;LIMIT&#39; in the SQL query. Can we do simple LIMIT with doctrine 2 ?

Set LIMIT with doctrine 2?

How do `opaque` `alpha` and the opacity of the background work together for a UIView and what are the differences between them?


![UIView](http://i.minus.com/jb2IP8TXbYTxKr.png)

UIView: opaque vs. alpha vs. opacity

I am wondering what the `atomically:` parameter stands for in the `writeToFile:atomically:` method (`-[NSArray writeToFile:atomically:]` for example). It is common to pass `YES` for `atomically:`, but I don&#39;t know what it means.

writeToFile:atomically: what does atomically mean?

<p>I am wondering what the <code>atomically:</code> parameter stands for in the <code>writeToFile:atomically:</code> method (<code>-[NSArray writeToFile:atomically:]</code> for example). It is common to pass <code>YES</code> for <code>atomically:</code>, but I don't know what it means.</p>


Ideally, i would want the entire interface to have a **custom styling** that is seen on the ios (itouch / ipad) or android equivalent with the virtual keyboard present. See below for more details.

A custom set CSS hacking rules to be active, when the keyboard is &quot;present&quot;, is also an acceptable solution.

Targets both androids and ios, on a website (HTML/JavaScript/CSS)
Also note that the layout inside is: **&quot;fluid&quot;.**

**Edit:** This was more design, then text; So the changes are not disorientating. At the lowest level, I just desire a design change with and without the virtual keys **(Perhaps just a background change).** 

**The question on which, this is a good or bad design idea, is debatable. However, I feel is irrelevant to the question. For such an exploit can have uses more then text (such as games, or interactive media).**

**Hence the bounty:** Despite no longer needing the answer for the project I was working on (an alternative design was used). I still believe this question can benefit from being answered.

**Default Behavior** 

                           +--------+ 
                           |        |
    +------------+       +-+-hidden-+-+   &lt;- ~50% hidden
    | +--------+ |       | +--------+ |
    | |        | |       | |visible | |
    | |        | |   \   | |        | |   &lt;- ~50% visible
    | |  100%  | |  ==&gt;  | +--------+ |
    | |        | |   /   | |virtual | |
    | |        | |       | |  keys  | |
    | +--------+ |       | +--------+ |
    +------------+       +------------+

**Desired Behavior** 


    +------------+       +------------+   
    | +--------+ |       | +--------+ |
    | |        | |       | |visible | |   &lt;- 100% visible (example styling)
    | |        | |   \   | |        | |      Custom Styling
    | |  100%  | |  ==&gt;  | +--------+ |
    | |        | |   /   | |virtual | |
    | |        | |       | |  keys  | |
    | +--------+ |       | +--------+ |
    +------------+       +------------+


screen styling when virtual keyboard is active

I&#39;m customizing a `UITableView`. I want to hide the line separating on the *last* cell ... can i do this?

I know I can do `tableView.separatorStyle = UITableViewCellStyle.None` but that would affect *all* the cells of the tableView. I want it to only affect my last cell.

Hide separator line on one UITableViewCell

Thanks for reading.

I am new to iOS and I am trying to upload an Image and a text using &lt;code&gt;multi-part form encoding&lt;/code&gt; in iOS. 

The &lt;code&gt;curl&lt;/code&gt; equivalent is something like this: &lt;code&gt;curl -F &quot;param1=value1&quot; -F &quot;param2=@testimage.jpg&quot; &quot;http://some.ip.address:5000/upload&quot;&lt;/code&gt;

The &lt;code&gt;curl&lt;/code&gt; command above returns the expected correct response in &lt;code&gt;JSON.&lt;/code&gt;

**Problem:** 
I keep getting a HTTP 400 request which means I am doing something wrong while composing the HTTP POST Body. 

**What I Did:**
For some reference, I tried  https://stackoverflow.com/questions/4683559/flickr-api-ios-app-post-size-too-large and https://stackoverflow.com/questions/5422028/objective-c-how-to-upload-image-and-text-using-http-post. But, I keep getting a HTTP 400. 

I tried the &lt;code&gt;ASIHttpRequest&lt;/code&gt; but had a different problem there (the callback never got called). But, I didn&#39;t investigate further on that since I&#39;ve heard the developer has stopped supporting the library: http://allseeing-i.com/[request_release]; 

Could someone please help me out?


ios Upload Image and Text using HTTP POST

For better re-usability I want to create a table view outside of my Storyboard.

Now when I create a `UITableView` based ViewController with Nib in Xcode I get the default TableView in the nib file. However, I am not able in Interface Builder to add prototype cells like I am in my Storyboard.

Is it currently not possible to add prototype cells in a nib or am I missing something.

Thanks very much for any help.

Prototype Cells in a nib instead of a storyboard

I&#39;m adapting [This tutorial][1] to my app, and I&#39;ve got it boiled down to one last error, which is stopping me in my tracks. The program is unable to find a property in another file, but that property is clearly defined. Here is the code in question:

The actual error line:

 

    for (DTContact *dtc in _dtContact.contact) {

the .h for the file, and items in question:

    #import &lt;UIKit/UIKit.h&gt;
    
    @class XMLTestViewController;
    @class DTCXMLResponse;
    
    @interface XMLTestController : UIViewController{
        UIWindow *window;
        XMLTestViewController *viewController;
        DTCXMLResponse *_dtContact;
    }
    
    
    @property (nonatomic, retain) IBOutlet UIWindow *window;
    @property (nonatomic, retain) IBOutlet XMLTestViewController *viewController;
    @property (nonatomic, retain) DTCXMLResponse *dtContact;
    
    @property (nonatomic, retain) IBOutlet UIButton *mybutton;
    -(IBAction)buttonClicked;
    
    @end

It&#39;s having issues with the _dtContact.contact. It can&#39;t find the contact in the file DTCXMLResponse. Here is the .h file and the section of the .m:

.h

    #import &lt;Foundation/Foundation.h&gt;
    
    @interface DTContactXMLResponse : NSObject {
        NSMutableArray *_contact;
    }
    
    @property (nonatomic, retain) NSMutableArray *contact;
    
    @end

.m

    #import &quot;DTCXMLResponse.h&quot;
    
    @implementation DTContactXMLResponse
    @synthesize contact = _contact;
    
    - (id)init {
        
        if ((self = [super init])) {
            self.contact = [[NSMutableArray alloc] init];
        }
        return self;
        
    }
    
    @end


So theres that. As you can see, I have &#39;contact&#39; propertied in the DTCXMLResponse.h, and linked in the .m. 
  [1]: http://www.raywenderlich.com/725/how-to-read-and-write-xml-documents-with-gdataxml


Property cannot be found in forward class object

I have an NSArray that I want to filter out certain objects using an NSPredicate, I was hoping I could use NOT IN since I saw that I can easily do an IN.

So I have my array:

    self.categoriesList

Then I get the values I want to remove:

    NSArray *parentIDs = [self.cateoriesList valueForKeyPath:@&quot;@distinctUnionOfObjects.ParentCategoryID&quot;];

This gives me a list of ParentCategoryID&#39;s for categories I DO NOT want to display, so I figure I can use an NSPredicate to remove them:

    self.cateoriesList = [self.cateoriesList filteredArrayUsingPredicate:[NSPredicate predicateWithFormat:@&quot;CategoryID NOT IN %@&quot;,parentIDs]];

This fails:

    reason: &#39;Unable to parse the format string &quot;CategoryID NOT IN %@&quot;&#39;

If I wanted to use just IN that works perfectly of course.
 

NSArray with NSPredicate using NOT IN

I&#39;m trying to implement AQRecorder.h class from SpeakHere Apple Xcode project example, but even I rename my implementation class to ext. `*.mm` and put line with `#import &quot;AQRecorder.h&quot;` still getting error `&quot;Unknown type name &#39;class&#39;; did you mean &#39;Class&#39;?&quot;` and many others.
Which according to me means that it is not recognized as C++ class.

Any help will be appreciated.

Unknown type name &#39;class&#39;; did you mean &#39;Class&#39;?

Just want to make sure that I got it right:

 1. Do I need to `__unsafe_unretain` objects that I don&#39;t own?
 2. If an object is `__unsafe_unretained` Do I need to use `assign` in the `@property`? Does that mean that the object is not retained, and just refers to the object I assign to?
 3. When would I want to use it except of delegates?
 4. Is that an ARC thing or was it in use before?

ARC - The meaning of __unsafe_unretained?

[![enter image description here][1]][1]

IF I wanted a picker, for states/provinces, i haven&#39;t seen an example, but I mocked up shown above, a picker for US/Can/Mex. wondering can you dynamically switch the NSMutableArray for the UIPickerView and then have it somehow reload each time you click on US/Can/Mex buttons???  How do I go about doing this.  What approach do I take.  Looking for someone to point a beginner for a clue in the right direction.  

 


  [1]: https://i.stack.imgur.com/5ATRG.jpg

How do I reload/refresh the UIPickerView (with new data array) based on button press?

A while ago I was experimenting, trying to see if i could get navigation items to animate and scroll between each other.

I don&#39;t know if this is related but suddenly without touching the simulator options I&#39;m getting this message `Simulator slow-motion animations are now on` and moving between views is very slow, like 3 seconds. This occurs with all animation effects.

Any idea what I need to do to stop this ?

Simulator slow-motion animations are now on?

I&#39;m developing an iOS 4 application using iOS SDK latest version and XCode 4.2.

I have a XIB with a `UIWebView` with **Alpha = 1.0**, **Background** set to **Clear Color** and **Opaque** is not set. On this XIB I setup an image as background with this code:

    - (id)initWithNibName:(NSString *)nibNameOrNil bundle:(NSBundle *)nibBundleOrNil
    {
        self = [super initWithNibName:nibNameOrNil bundle:nibBundleOrNil];
        if (self) {
            UIColor *background = [[UIColor alloc] initWithPatternImage:[UIImage imageNamed:@&quot;AboutBackground.png&quot;]];
            self.view.backgroundColor = background;
            [background release];
        }
        return self;
    }

The `UIWebView` is showing an static html:

    &lt;html&gt;&lt;head&gt;&lt;/head&gt;&lt;body style=\&quot;margin:0 auto;text-align:center;background-color: transparent; color:white\&quot;&gt;...&lt;/body&gt;&lt;/html&gt;

On iOS 5 simulator, its background is transparent, but on an iOS 4 device is grey.

Any clue?


UIWebView background is set to Clear Color, but it is not transparent

I&#39;m allocating a UIButtonTypeCustom UIButton to a UIView with a background image that is smaller than the button&#39;s frame. Reason why the image is smaller is because I&#39;m trying to add more of a &quot;target area&quot; for the UIButton. However, the image is being scaled to the full size of the frame, rather than just being the image&#39;s size.

I have tried setting the UIButton and UIButton&#39;s imageView contentMode property to &quot;UIViewContentModeScaleAspectFit&quot;, but no luck, the image still gets stretched out.

Is there a way to do what I&#39;m trying to do programmatically?

Thanks in advance!

How do I prevent a button&#39;s background image from stretching?

Can anyone explain what is `std::memory_order` in plain English, and how to use them with `std::atomic&lt;&gt;`?

I found the reference and few examples here, but don&#39;t understand at all.
http://en.cppreference.com/w/cpp/atomic/memory_order


c++, std::atomic, what is std::memory_order and how to use them?

How do atomic / volatile / synchronized work internally?

What is the difference between the following code blocks?

Code 1

    private int counter;
    
    public int getNextUniqueIndex() {
        return counter++; 
    }

Code 2

    private AtomicInteger counter;
    
    public int getNextUniqueIndex() {
        return counter.getAndIncrement();
    }

Code 3

    private volatile int counter;
    
    public int getNextUniqueIndex() {
        return counter++; 
    }

---

Does `volatile` work in the following way? Is

    volatile int i = 0;
    void incIBy5() {
        i += 5;
    }

equivalent to 

    Integer i = 5;
    void incIBy5() {
        int temp;
        synchronized(i) { temp = i }
        synchronized(i) { i = temp + 5 }
    }


I think that two threads cannot enter a synchronized block at the same time... am I right? If this is true then how does `atomic.incrementAndGet()` work without `synchronized`? And is it thread-safe?

And what is the difference between internal reading and writing to volatile variables / atomic variables? I read in some article that the thread has a local copy of the variables - what is that?

What is the difference between atomic / volatile / synchronized?

Now that C++11 has multithreading I was wondering what is the correct way to implement lazy initialized singleton without using mutexes(for perf reasons).
I came up with this, but tbh Im not really good at writing lockfree code, so Im looking for some better solutions.

    // ConsoleApplication1.cpp : Defines the entry point for the console application.
    //
    # include &lt;atomic&gt;
    # include &lt;thread&gt;
    # include &lt;string&gt;
    # include &lt;iostream&gt;
    using namespace std;
    class Singleton
    {
    
    public:
    	Singleton()
    	{
    	}
    static	bool isInitialized()
    	{
    		return (flag==2);
    	}
    static	bool initizalize(const string&amp; name_)
    	{
    		if (flag==2)
    			return false;// already initialized
    		if (flag==1)
    			return false;//somebody else is initializing
    		if (flag==0)
    		{
    			int exp=0;
    			int desr=1;
    			//bool atomic_compare_exchange_strong(std::atomic&lt;T&gt;* obj, T* exp, T desr)
    			bool willInitialize=std::atomic_compare_exchange_strong(&amp;flag, &amp;exp, desr);
    			if (! willInitialize)
    			{
    				//some other thread CASed before us
    				std::cout&lt;&lt;&quot;somebody else CASed at aprox same time&quot;&lt;&lt; endl;
    				return false;
    			}
    			else 
    			{
    				initialize_impl(name_);
    				assert(flag==1);
    				flag=2;
    				return true;
    			}
    		}
    	}
    static void clear()
    {
    	name.clear();
    	flag=0;
    }
    private:
    static	void initialize_impl(const string&amp; name_)
    {
    		name=name_;
    }
    static 	atomic&lt;int&gt; flag;
    static  string name;
    };
    atomic&lt;int&gt; Singleton::flag=0;
    string Singleton::name;
    void myThreadFunction()
    {
    	Singleton s;
    	bool initializedByMe =s.initizalize(&quot;1701&quot;);
    	if (initializedByMe)
    		s.clear();
    	
    }
    int main()
    {
    	while (true)
    	{
    		std::thread t1(myThreadFunction);
    		std::thread t2(myThreadFunction);
    		t1.join();
    	    t2.join();
    	}
    	return 0;
    }
Note that `clear()` is just for testing, real singleton wouldnt have that function.


How to implement multithread safe singleton in C++11 without using &lt;mutex&gt;

Is there a systematic way to know whether an operation in C# will be atomic or not?  Or are there any general guidelines or rules of thumb?

What operations are atomic in C#?

I read a chapter and I didn&#39;t like it much. I&#39;m still unclear what the differences is between each memory order. This is my current speculation which I understood after reading the much more simple http://en.cppreference.com/w/cpp/atomic/memory_order

**The below is wrong so don&#39;t try to learn from it**

- memory_order_relaxed: Does not sync but is not ignored when order is done from another mode in a different atomic var
- memory_order_consume: Syncs reading this atomic variable however It doesnt sync relaxed vars written before this. However if the thread uses var X when modifying Y (and releases it). Other threads consuming Y will see X released as well? I don&#39;t know if this means this thread pushes out changes of x (and obviously y)
- memory_order_acquire: Syncs reading this atomic variable AND makes sure relaxed vars written before this are synced as well. (does this mean all atomic variables on all threads are synced?)
- memory_order_release: Pushes the atomic store to other threads (but only if they read the var with consume/acquire)
- memory_order_acq_rel: For read/write ops. Does an acquire so you don&#39;t modify an old value and releases the changes.
- memory_order_seq_cst: The same thing as acquire release except it forces the updates to be seen in other threads (if `a` store with relaxed on another thread. I store `b` with seq_cst. A 3rd thread reading `a`  with relax will see changes along with `b` and any other atomic variable?).

I think I understood but correct me if i am wrong. I couldn&#39;t find anything that explains it in easy to read english.


Content Type	Original Author	Original Content on Stackoverflow
Question	JonasG	View Question on Stackoverflow
Solution 1 - Ios	Jack Danger	View Answer on Stackoverflow
Solution 2 - Ios	Darko Kenda	View Answer on Stackoverflow

writeToFile:atomically: what does atomically mean?

Ios Problem Overview

Ios Solutions

Solution 1 - Ios

Solution 2 - Ios

UIView: opaque vs. alpha vs. opacity

Set LIMIT with doctrine 2?

Attributions