I believe that the stringWithFormat specifiers are the standard [IEEE printf specifiers](http://pubs.opengroup.org/onlinepubs/009695399/functions/printf.html). Have you tried

    [NSString stringWithFormat:@&quot;%02d&quot;, 1];


Use the format string `%02d`. This specifies to format an integer with a minimum field-width of 2 characters and to pad the formatted values with 0 to meet that width. See `man fprintf` for all the gory details of format specifiers.

If you are formatting numbers for presentation to the user, though, you should really be using `NSNumberFormatter`. Different locales have wildly different expectations about how numbers should be formatted.

    [NSString stringWithFormat:@&quot;%00.02d&quot;, intValue]

This help me to convert 1 to 01.

I&#39;m developing a web app that apparently is having problems in iOS devices. The problem is that I don&#39;t own an iOS device and I develop in Linux Ubuntu. I&#39;m looking for a way to emulate/simulate this OS in Linux (especially the browser), but haven&#39;t found anything.

So far, what I&#39;ve found is the iOS SDK&#39;s Simulator, but that is meant for the Mac. And also some emulator for Windows. Has anyone done this before?

Emulate/Simulate iOS in Linux

I have a Navigation Bar in a view, and I want to change its Navigation Item title programmatically.

How is this done?

How to set the title of a Navigation Bar programmatically?

How can I have a two-digit integer in a a string, even if the integer is less than 10?

    [NSString stringWithFormat:@&quot;%d&quot;, 1] //should be @&quot;01&quot;


Make a two-digit string from a single-digit integer

How can I have a two-digit integer in a a string, even if the integer is less than 10?
<pre><code class="hljs language-bash">[NSString stringWithFormat:@"%d", 1] //should be @"01"
</code></pre>

In the Mac and iOS platforms, memory leaks are often caused by unreleased pointers. Traditionally, it has always been of utmost importance to check your allocs, copies and retains to make sure each has a corresponding release message.

The toolchain that comes with Xcode 4.2 introduces automatic reference counting (ARC) with the latest version of the [LLVM compiler](http://llvm.org), that totally does away with this problem by getting the compiler to memory-manage your stuff for you. That&#39;s pretty cool, and it does cut lots of unnecessary, mundane development time and prevent a lot of careless memory leaks that are easy to fix with proper retain/release balance. Even autorelease pools need to be managed differently when you enable ARC for your Mac and iOS apps (as you shouldn&#39;t allocate your own `NSAutoreleasePool`s anymore).

But what *other* memory leaks does it *not* prevent that I still have to watch out for?

As a bonus, what are the differences between ARC on Mac OS X and iOS, and garbage collection on Mac OS X?

What kind of leaks does automatic reference counting in Objective-C not prevent or minimize?

I need to create a CGSize to compute text height of an arbitrary text with arbitrary length. UIKit has this nice method -sizeWithFont:constrainedToSize: and my text is only constrained in width, but not in height.

For this, I need to set the maximum possible CGFloat for the height.

Is there a constant like &quot;CGFloatMax&quot;?

Is there a constant for the maximum CGFloat value?

I am currently receiving a string like this:

    @&quot;Sam|26,Hannah|22,Adam|30,Carlie|32,Jan|54&quot;

And I am splitting it like this:

    testArray = [[NSArray alloc] init];
    NSString *testString = [[NSString alloc] initWithFormat:@&quot;Sam|26,Hannah|22,Adam|30,Carlie|32,Jan|54,Steve|56,Matty|24,Bill|30,Rob|30,Jason|33,Mark|22,Stuart|54,Kevin|30&quot;];
    testArray = [testString componentsSeparatedByString:@&quot;,&quot;];
    	
    dict = [NSMutableDictionary dictionary];
    for (NSString *s in testArray) {
    		
        testArray2 = [s componentsSeparatedByString:@&quot;|&quot;];
        [dict setObject:[testArray2 objectAtIndex:1] forKey:[testArray2 objectAtIndex:0]];
    }

I will now be receiving a string like this:

    @&quot;Sam|26|Developer,Hannah|22|Team Leader,Adam|30|Director,Carlie|32|PA,Jan|54|Cleaner&quot;

Can I (and how) use the same method as above to separate the string more than once using the &quot;|&quot; separator?

Split NSString multiple times on the same separator

Let&#39;s say I have an `NSURL`? Whether or not it already has an empty query string, how do I add one or more parameters to the `query` of the `NSURL`? I.e., does anyone know of an implementation of this function?

    - (NSURL *)URLByAppendingQueryString:(NSString *)queryString

So that it satisfies this `NSURL+AdditionsSpec.h` file:

    #import &quot;NSURL+Additions.h&quot;
    #import &quot;Kiwi.h&quot;
    
    SPEC_BEGIN(NSURL_AdditionsSpec)
    
    describe(@&quot;NSURL+Additions&quot;, ^{
        __block NSURL *aURL;
    
        beforeEach(^{
            aURL = [[NSURL alloc] initWithString:@&quot;http://www.example.com&quot;];
            aURLWithQuery = [[NSURL alloc] initWithString:@&quot;http://www.example.com?key=value&quot;];
        });
    
        afterEach(^{
            [aURL release];
            [aURLWithQuery release];
        });
    
        describe(@&quot;-URLByAppendingQueryString:&quot;, ^{
            it(@&quot;adds to plain URL&quot;, ^{
                [[[[aURL URLByAppendingQueryString:@&quot;key=value&amp;key2=value2&quot;] query] should]
                 equal:@&quot;key=value&amp;key2=value2&quot;];
            });
    
            it(@&quot;appends to the existing query sting&quot;, ^{
                [[[[aURLWithQuery URLByAppendingQueryString:@&quot;key2=value2&amp;key3=value3&quot;] query] should]
                 equal:@&quot;key=value&amp;key2=value2&amp;key3=value3&quot;];
            });
        });
    });
    
    SPEC_END




Objective-C: How to add query parameter to NSURL?

I just created a singleton method, and I would like to know what the function `@synchronized()` does, as I use it frequently, but do not know the meaning.

What does @synchronized() do as a singleton method in objective C?

As the title says, I&#39;ve got a string and I want to split into segments of **n** characters.

For example:

    var str = &#39;abcdefghijkl&#39;;

after some magic with `n=3`, it will become

    var arr = [&#39;abc&#39;,&#39;def&#39;,&#39;ghi&#39;,&#39;jkl&#39;];

Is there a way to do this?

How can I split a string into segments of n characters?

Say I have the following string:

    &quot;abcdefghijklmnopqrstuvwxyz&quot;

And I think its too long for one line in my YAML file, is there some way to split that over several lines?

    &gt;-
        abcdefghi
        jklmnopqr
        stuvwxyz

Would result in `&quot;abcdefghi jklmnopqr stuvwxyz&quot;` which is close, but it shouldn&#39;t have any spaces.

Is there a way to represent a long string that doesnt have any whitespace on multiple lines in a YAML document?

Apparently, the following is the valid syntax:

    b&#39;The string&#39;

I would like to know:

 1. What does this `b` character in front of the string mean?
 2. What are the effects of using it?
 3. What are appropriate situations to use it?

I found a [related question][1] right here on SO, but that question is about PHP though, and it states the `b` is used to indicate the string is binary, as opposed to Unicode, which was needed for code to be compatible from version of PHP &lt; 6, when migrating to PHP 6. I don&#39;t think this applies to Python.

I did find [this documentation][2] on the Python site about using a `u` character in the same syntax to specify a string as Unicode. Unfortunately, it doesn&#39;t mention the **b** character anywhere in that document.

Also, just out of curiosity, are there more symbols than the `b` and `u` that do other things?

  [1]: https://stackoverflow.com/q/4749442/346561
  [2]: http://docs.python.org/tutorial/introduction.html#unicode-strings

What does the &#39;b&#39; character do in front of a string literal?

How do you trim whitespace from the start and end of a string?

    trim &quot;  abc &quot; 

    =&gt;

    &quot;abc&quot;

Edit:

Ok, let me be a little clearer. I did not understand that string literals were treated so differently from Strings.

I would like to do this:

    import qualified Data.Text as T
    let s :: String = &quot;  abc  &quot;
    in T.strip s

Is this possible in Haskell? I am using -XOverloadedStrings but that appears only to work for literals.

In Haskell, how do you trim whitespace from the beginning and end of a string?

I have a string called &quot;hello world&quot;

I need to replace the word &quot;world&quot; to &quot;csharp&quot;

for this I use:

    string.Replace(&quot;World&quot;, &quot;csharp&quot;);

but as a result, I don&#39;t get the string replaced. The reason is case sensitiveness. The original string contains &quot;world&quot; whereas I&#39;m trying to replace &quot;World&quot;.

Is there any way to avoid this case sensitiveness in string.Replace method?

String.Replace ignoring case

I have been learning a lot about writing Objective-C code and designing in Interface Builder and I wanted to set icons for my simple programs.

I added the same JPG to all the size fields in Icon Composer and got an ICNS, but I couldn&#39;t figure out how to add it to the project.

Thank you in advance.

How can I set the icon for a Mac Application in Xcode?

Bear with me, this is going to take some explaining. I have a function that looks like the one below.

Context: &quot;aProject&quot; is a Core Data entity named LPProject with an array named &#39;memberFiles&#39; that contains instances of another Core Data entity called LPFile. Each LPFile represents a file on disk and what we want to do is open each of those files and parse its text, looking for @import statements that point to OTHER files. If we find @import statements, we want to locate the file they point to and then &#39;link&#39; that file to this one by adding a relationship to the core data entity that represents the first file. Since all of that can take some time on large files, we&#39;ll do it off the main thread using GCD.



    - (void) establishImportLinksForFilesInProject:(LPProject *)aProject {
        dispatch_queue_t taskQ = dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0);
         for (LPFile *fileToCheck in aProject.memberFiles) {
             if (//Some condition is met) {
                dispatch_async(taskQ, ^{
                    // Here, we do the scanning for @import statements. 
                    // When we find a valid one, we put the whole path to the imported file into an array called &#39;verifiedImports&#39;. 
                
                    // go back to the main thread and update the model (Core Data is not thread-safe.)
                    dispatch_sync(dispatch_get_main_queue(), ^{
                                
                        NSLog(@&quot;Got to main thread.&quot;);
                                
                        for (NSString *import in verifiedImports) {  
                                // Add the relationship to Core Data LPFile entity.
                        }
                    });//end block
                });//end block
            }
        }
    }



Now, here&#39;s where things get weird:

This code works, but I&#39;m seeing an odd problem. If I run it on an LPProject that has a few files (about 20), it runs perfectly. However, if I run it on an LPProject that has more files (say, 60-70), it does **NOT** run correctly. We never get back to the main thread, the `NSLog(@&quot;got to main thread&quot;);` never appears and the app hangs. BUT, (and this is where things get REALLY weird) --- if I run the code on the small project FIRST and THEN run it on the large project, everything works perfectly. It&#39;s ONLY when I run the code on the large project first that the trouble shows up.

And here&#39;s the kicker, if I change the second dispatch line to this:

    dispatch_async(dispatch_get_main_queue(), ^{

(That is, use `async` instead of `sync` to dispatch the block to the main queue), everything works all the time. Perfectly. Regardless of the number of files in a project! 

I&#39;m at a loss to explain this behavior. Any help or tips on what to test next would be appreciated. 

dispatch_sync vs. dispatch_async on main queue

I want to enable NSLog when I am in debug and disable it otherwise. A very simple thing is:

    #ifdef DEBUG
    NSLog(@&quot;My log&quot;);
    #endif

But all this `#ifdef` and `#endif` is borring... :( So I try other thing: (.pch is good place to put it)

    #ifdef DEBUG
    #   define NSLog(text) NSLog(text);
    #else 
    #   define NSLog(text) 
    #endif

This work very fine (isn&#39;t recursive). But the problem is that NSLog have infinite arguments.

    void NSLog(NSString *format, ...)

How I solve this to work in preprocessor mode?

-- Edit -- 

This code make your NSLog better: 

    #ifdef DEBUG
        #define NSLog(FORMAT, ...) fprintf(stderr,&quot;%s\n&quot;, [[NSString stringWithFormat:FORMAT, ##__VA_ARGS__] UTF8String]);
    #else
        #define NSLog(...)
    #endif

Enable and Disable NSLog in DEBUG mode

I am using the Xcode beta for developers, and am noticing some subtle differences. Among them is a new attribute for declared properties.

    @property(strong)IBOutlet NSArrayController *arrayControl;

My question is: what does the strong attribute mean?? Does it replace some older one, or is it something entirely new? I have searched through google and the developer documentation and havent been able to find anything. Until i know what it is i am hesitant to use it.

Thanks in advance

What is the strong property attribute

I have an enum holding several values:

**enum {value1, value2, value3}  myValue;**

In a certain point in my app, I wish to check which value of the enum is now active. I&#39;m using NSLog but I&#39;m not clear on how to display the current value of the enum (value1/valu2/valu3/etc...) as a NSString for the NSLog.

Anyone?

enum Values to NSString (iOS)

I have been googling so much on how to do this, but how would I reverse a NSString? Ex:hi would become: ih

I am looking for the easiest way to do this.

Thanks!

@Vince I made this method:

    - (IBAction)doneKeyboard {
    
    // first retrieve the text of textField1
    NSString *myString = field1.text;
    NSMutableString *reversedString = [NSMutableString string];
    NSUInteger charIndex = 0;
    while(myString &amp;&amp; charIndex &lt; [myString length]) {
        NSRange subStrRange = NSMakeRange(charIndex, 1);
        [reversedString appendString:[myString substringWithRange:subStrRange]];
        charIndex++;
    }
    // reversedString is reversed, or empty if myString was nil
    field2.text = reversedString;
    }

I hooked up that method to textfield1&#39;s didendonexit. When I click the done button, it doesn&#39;t reverse the text, the UILabel just shows the UITextField&#39;s text that I entered. What is wrong?


Reverse NSString text

I have Constants NSString, that I want to call like:

    [newString isEqualToString:CONSTANT_STRING];

Any wrong code here?

I got this warning:

&gt; sending &#39;const NSString *&#39; to parameter of type &#39;NSString *&#39; discards qualifiers

How should these be declared?

&quot;sending &#39;const NSString *&#39; to parameter of type &#39;NSString *&#39; discards qualifiers&quot; warning

Hi I am woundering if you can check to see if a NSString equals a specific value say for instance a name of a person?

I am thinking along the lines of

    if (mystring == @&quot;Johns&quot;){
        //do some stuff in here
    }



how to check if NSString = a specific string value?

How can I display this:

Decimal(&#39;40800000000.00000000000000&#39;) as &#39;4.08E+10&#39;?

I&#39;ve tried this:

    &gt;&gt;&gt; &#39;%E&#39; % Decimal(&#39;40800000000.00000000000000&#39;)
    &#39;4.080000E+10&#39;

But it has those extra 0&#39;s.



Display a decimal in scientific notation

I have got a price field to display which sometimes can be either 100 or 100.99 or 100.9, What I want is to display the price in 2 decimal places only if the decimals are entered for that price , for instance if its 100 so it should only show 100 not 100.00 and if the price is 100.2 it should display 100.20 similarly for 100.22 should be same .
I googled and came across some examples but they didn&#39;t match exactly what i wanted :

    // just two decimal places
    String.Format(&quot;{0:0.00}&quot;, 123.4567);      // &quot;123.46&quot;
    String.Format(&quot;{0:0.00}&quot;, 123.4);         // &quot;123.40&quot;
    String.Format(&quot;{0:0.00}&quot;, 123.0);         // &quot;123.00&quot;

Using String Format to show decimal up to 2 places or simple integer

I want to write a method that will take an integer and return a `std::string` of that integer formatted with commas.

Example declaration:

    std::string FormatWithCommas(long value);

Example usage:

    std::string result = FormatWithCommas(7800);
    std::string result2 = FormatWithCommas(5100100);
    std::string result3 = FormatWithCommas(201234567890);
    // result = &quot;7,800&quot;
    // result2 = &quot;5,100,100&quot;
    // result3 = &quot;201,234,567,890&quot;

What is the C++ way of formatting a number as a `string` with commas?

(Bonus would be to handle `double`s as well.)

c++: Format number with commas?

There are way too many questions and answers about this basic functionality, I cannot see the wood for the trees. 

In Java there is only one simple answer (`java.text.NumberFormat` and its subclasses) so I&#39;m sure the majority of plugins, questions and answers will mature eventually to a de-facto standard for JQuery.

**This plugin** is the best I found so far, but I don&#39;t know if it&#39;s still developed, is mature etc.

http://plugins.jquery.com/project/numberformatter

Is there a better solution? Is it mature / active enough to rely on?


----------

**Edit:**

I would like to be able to format currencies, decimal, integers based on the same format patterns Java uses, so that data recieved on the client side can be formatted without sending it first to the server. 

e.g. 

Format `1000` to `$1,000` or `1,000.00` etc (locale support is nice)

Seems that http://plugins.jquery.com/project/numberformatter does the job but the question was: &quot;Am I using the right thing?&quot; or &quot;Is there a better way to do so?&quot;





JQuery Number Formatting

How could I convert from float to string or string to float?
  
In my case I need to make the assertion between 2 values string (value that I have got from table) and float value that I have calculated.

    String valueFromTable = &quot;25&quot;;
    Float valueCalculated =25.0;

I tried from float to string:
 
    String sSelectivityRate = String.valueOf(valueCalculated);

but the assertion fails 


Content Type	Original Author	Original Content on Stackoverflow
Question	aneuryzm	View Question on Stackoverflow
Solution 1 - Objective C	highlycaffeinated	View Answer on Stackoverflow
Solution 2 - Objective C	Jeremy W. Sherman	View Answer on Stackoverflow
Solution 3 - Objective C	user2357514	View Answer on Stackoverflow

Make a two-digit string from a single-digit integer

Objective C Problem Overview

Objective C Solutions

Solution 1 - Objective C

Solution 2 - Objective C

Solution 3 - Objective C

How to set the title of a Navigation Bar programmatically?

Emulate/Simulate iOS in Linux

Attributions