`NSMutableArray` (and all other classes with `Mutable` in the name) can be modified. So, if you create a plain `NSArray`, you cannot change its contents later (without recreating it). But if you create an `NSMutableArray`, you can change it — you&#39;ll notice it has methods like `-addObject:` and `-insertObject:atIndex:`.

See [the documentation](https://developer.apple.com/library/mac/documentation/Cocoa/Reference/Foundation/Classes/NSMutableArray_Class/) for details.

The &quot;mutable&quot; types are classes which can be changed after they&#39;ve been initialized, like `NSMutableString` vs `NSString`.

NSArray : in NSArray we can not change index....
          Means fix array.

NSMutableArray : in NSMutableArray we can change index and also add the value in array at run-time..


Say I have 2 parallel collections, eg: a list of people&#39;s names in a `List&lt;String&gt;` and a list of their age in a `List&lt;Int&gt;` in the same order (so that any given index in each collection refers to the same person).

I want to iterate through both collections at the same time and fetch the name and age of each person and do something with it. With arrays this is easily done with:

    for (int i = 0; i &lt; names.length; i++) {
       do something with names[i] ....
       do something with ages[i].....
    }

What would be the most elegant way (in terms of readability and speed) of doing this with collections?


How to most elegantly iterate through parallel collections?

Now I want to display some unicode characters and I have used tag: `&lt;font face=&quot;
Arial&quot;&gt;something here&lt;/font&gt;`. But it seems that `WebView` can not find the Arial
font because I can only see UFO-characters. Do I have to copy arial.ttf to
somewhere or how can I use this TrueType font with `WebView`? Thanks.

 How to use custom font with WebView

What is the difference b/w `NSArray` and `NSMutableArray`?

Difference between NSArray and NSMutableArray

<p>What is the difference b/w <code>NSArray</code> and <code>NSMutableArray</code>?</p>


I am trying to acquire a thumbnail (of the first frame) from a video taken from iphone 3GS camera so I can display it. How to do this?


Getting a thumbnail from a video url or data in iOS

How can I navigate through all my text fields with the &quot;Next&quot; Button on the iPhone Keyboard?

The last text field should close the Keyboard.

I&#39;ve setup the IB the Buttons (Next / Done) but now I&#39;m stuck.

I implemented the textFieldShouldReturn action but now the Next and Done Buttons close the Keyboard.


How to navigate through textfields (Next / Done Buttons)

I had a `UITextView` that detects phone numbers and links, but this overrides my `fontColor` and change it to `blueColor`. Is there a way to format the color of auto detected links, or should I try a manual version of this function?

Can I change the color of auto detected links on UITextView?

I am having a bit of trouble figuring out this Core Data stuff.  How do I create a new entry with a unique ID?  In SQL I would just declare one field as an autoincrement field.  I&#39;m not seeing anything like that here, but I could just be missing something.  I just want an auto incrementing NSInteger field, so when I manually add items to the database, I will have some form of reference to them.

Creating a unique id for a Core Data program on the iPhone

I have a uitableview that loads fairly large images in each cell and the cell heights vary depending on the size of the image. Scrolling performance is decent, but can sometimes be jerky. 

I found these tips I found on the FieryRobot blog:

[glassy-scrolling-with-uitableview][1]

[more-glassy-scrolling-with-uitableview][2]

Does anyone have any tips for improving uitableview scrolling performance?


  [1]: http://www.fieryrobot.com/blog/2008/10/01/glassy-scrolling-with-uitableview/
  [2]: http://www.fieryrobot.com/blog/2008/10/08/more-glassy-scrolling-with-uitableview/

Tricks for improving iPhone UITableView scrolling performance?

I have a UITableView displaying a list of Cities.
I want to separate them by State.  I can&#39;t seem to figure out how to get it to pick the right items out of my Array.
If Section 1 (Arizona) has 2 Cities and Section 2 (California) has 2 Cities, during cellForRowAtIndexPath, Section 2, City 1 has an index of 0, even though it&#39;s the 3rd item in my array.
I thought about just turning my City Array into a State Array, where each item holds an Array of Cities, but I still don&#39;t know what section I&#39;m on and therefore don&#39;t know which City Array under the States Array I would need to access.


UITableView, how do I know what Section during cellForRowAtIndexPath?

How do I convert NSMutableArray to NSArray in [tag:Objective-C]?


  [1]: http://en.wikipedia.org/wiki/Objective-C

How do I convert NSMutableArray to NSArray?

I have declared an `NSMutableArray *categories` in my view controller .h file, and declared a property for it. 

In the `parser:foundCharacters:` method of the `NSXMLParser` delegate in my .m file, I have this code:

    -(void)parser:(NSXMLParser *) parser foundCharacters:(NSString *)string  
    {  
        if (elementFound)  
        {  
            element = string;  
            [self.categories addObject:element];  
        }  
    }

But when I hover over the `[self.categories addObject:element]` line after stepping into it in debug mode, XCode tells me the size is 0x0, 0 objects. There are 3 elements in my XML file so 3 items should be in the array.

I&#39;m missing something really obvious and I can&#39;t figure out what.

NSMutableArray addObject not working

What is the difference between `copy` and `mutableCopy` when used on either an `NSArray` or an `NSMutableArray`?


This is my understanding; is it correct?

    // ** NSArray **
    NSArray *myArray_imu = [NSArray  arrayWithObjects:@&quot;abc&quot;, @&quot;def&quot;, nil];
    
    // No copy, increments retain count, result is immutable
    NSArray *myArray_imuCopy = [myArray_imu copy];
    
    // Copys object, result is mutable 
    NSArray *myArray_imuMuta = [myArray_imu mutableCopy];
    
    // Both must be released later
    	
--- 
	
    // ** NSMutableArray **
    NSMutableArray *myArray_mut = [NSMutableArray arrayWithObjects:@&quot;A&quot;, @&quot;B&quot;, nil];
    	
    // Copys object, result is immutable
    NSMutableArray *myArray_mutCopy = [myArray_mut copy];
    
    // Copys object, result is mutable
    NSMutableArray *myArray_mutMuta = [myArray_mut mutableCopy];

    // Both must be released later
    

How do copy and mutableCopy apply to NSArray and NSMutableArray?

    NSArray *array = [[NSArray alloc] initWithObjects:@&quot;ΕΛΤΑ&quot;,
                          @&quot;ΕΛΤΑ COURIER&quot;, @&quot;ACS&quot;, @&quot;ACS ΕΞΩΤΕΡΙΚΟ&quot;, 
                          @&quot;DHL&quot;, @&quot;INTERATTICA&quot;, @&quot;SPEEDEX&quot;, 
                          @&quot;UPS&quot;, @&quot;ΓΕΝΙΚΗ ΤΑΧΥΔΡΟΜΙΚΗ&quot;, @&quot;ΜΕΤΑΦΟΡΙΚΕΣ ΕΞΩΤΕΡΙΚΟΥ&quot;, nil];

This is working because it has nil at the end.

But I add objects like this: `addObject:name` etc...
So at the end I have to add nil I do this addObhect:nil but when I run the app it still crashes at `cellForRowAtIndexPath:`

how can I do this work? 

Ok, I dont have to add nil

What is the reason that my app crashes then?

how to add nil to nsmutablearray?

I have an `NSArray` formed with objects of a custom class. The class has 3 (city, state, zip) string properties. I would like to get all unique state values from the `array`.

I did read through the `NSPredicate` class but couldn&#39;t make much of how to use it in this case. The only examples I could find were for string operations.

Can someone please help me out?

iPhone - getting unique values from NSArray object

I am new to Core Data. I have noticed that collection types are not available as attribute types and would like to know what the most efficient way is of storing array/dictionary type data as an attribute (e.g. the elements that make up an address like street, city, etc. does not require a separate entity and is more conveniently stored as a dictionary/array than separate attributes/fields). Thank you.

Best practice? - Array/Dictionary as a Core Data Entity Attribute

UIAlertSheet&#39;s constructor takes an otherButtonTitles parameter as a varg list. I&#39;d like to specify the other button titles from an NSArray instead. Is this possible?

i.e. I have to do this:

    id alert = [[UIActionSheet alloc] initWithTitle: titleString
                                      delegate: self
                                      cancelButtonTitle: cancelString
                                      destructiveButtonTitle: nil
                                      otherButtonTitles: button1Title, button2Title, nil];

But since I&#39;m generating the list of available buttons at runtime, I really want something like this:

    id alert = [[UIActionSheet alloc] initWithTitle: titleString
                                           delegate: self
                                  cancelButtonTitle: cancelString
                             destructiveButtonTitle: nil
                                  otherButtonTitles: otherButtonTitles];

Right now, I&#39;m thinking that I need to have a seperate call to `initWithTitle:` for 1 item, 2 items and 3 items. Like this:

    if ( [titles count] == 1 ) {
         alert = [[UIActionSheet alloc] initWithTitle: titleString
                                             delegate: self
                                    cancelButtonTitle: cancelString
                               destructiveButtonTitle: nil
                                    otherButtonTitles: [titles objectAtIndex: 0], nil];
    } else if ( [titles count] == 2) {
         alert = [[UIActionSheet alloc] initWithTitle: titleString
                                             delegate: self
                                    cancelButtonTitle: cancelString
                               destructiveButtonTitle: nil
                                    otherButtonTitles: [titles objectAtIndex: 0], [titles objectAtIndex: 1],  nil];
    } else {
        // and so on
    }

That&#39;s a lot of duplicate code, but it might actually be reasonable since I have at most three buttons. How can I avoid this?

Use NSArray to specify otherButtonTitles?

I am wondering how to convert an **NSArray** ` [@&quot;Apple&quot;, @&quot;Pear &quot;, 323, @&quot;Orange&quot;] ` to a string in **Objective-C**.

Content Type	Original Author	Original Content on Stackoverflow
Question	g.revolution	View Question on Stackoverflow
Solution 1 - Iphone	jtbandes	View Answer on Stackoverflow
Solution 2 - Iphone	Shaggy Frog	View Answer on Stackoverflow
Solution 3 - Iphone	Jagat Dave	View Answer on Stackoverflow

Difference between NSArray and NSMutableArray

Iphone Problem Overview

Iphone Solutions

Solution 1 - Iphone

Solution 2 - Iphone

Solution 3 - Iphone

How to use custom font with WebView

How to most elegantly iterate through parallel collections?

Attributions