NSArray by example

In this tutorial, we will be covering various functions available in NSArray. NSArray help us in creating static array.

Modern Objective C Array notations.

There is modern Objective C syntax that makes it easier for us to create and retrieve objects. Xcode actually changes to required format in build time. The syntax for initialization and accessing is as shown below.

	// initialization
	NSArray *array = @[@"Eezy", @"Tutorials"];
	// access value at index 0
	NSString *value = array[0];

Instance Methods

+ array

This method allows us creating a static empty array.

Example

	NSArray *array = [NSArray array];	
	
	NSLog(@"%@",array);


var array = NSArray()
	
print(array)

Output

2014-01-27 19:53:51.555 array[25037] ()

+ arrayWithObject:

This method allows us creating a static array with one object.

Example

	NSArray *array =  [NSArray arrayWithObject:@"Eezy"];	
	
	NSLog(@"%@",array);

	//Not available on swift

Output

2014-01-27 19:53:51.555 array[25037] ( Eezy )

+ arrayWithObjects:

This method allows us creating a static array with one object.

Example

	NSArray *array =  [NSArray arrayWithObjects:@"Eezy",@"Tutorials"];	
	
	NSLog(@"%@",array);

	//Not available on swift

Output

2014-01-27 19:53:51.555 array[25037] ( Eezy , Tutorials )

+ arrayWithArray:

This method allows us creating a static empty array.

Example

	NSArray *tempArray = [NSArray arrayWithObjects:@"Eezy",@"Tutorials"];

	NSArray *array =  [NSArray arrayWithArray:tempArray];	
	
	NSLog(@"%@",array);

var tempArray:NSArray = NSArray(array: ["Eezy","Tutorials"])

var array = NSArray(array: tempArray)

println(array)

Output

2014-01-27 19:53:51.555 array[25037] ( Eezy , Tutorials )

+ arrayWithContentsOfFile:

This method allows us to read an array from a apple propery list(plist) file.

Assuming we have the following data in plist in application bundle that is the plist is added to our project.

		<?xml version="1.0" encoding="UTF-8"?>
		<!DOCTYPE plist PUBLIC "-//Apple//DTD PLIST 1.0//EN" "http://www.apple.com/DTDs/PropertyList-1.0.dtd">
		<plist version="1.0">
		 <array>
			<string>Eezy</string>
			<string>Tutorials</string>
		</array>
		</plist>

Example

	
	NSString *file = [[NSBundle mainBundle] pathForResource:@"Data" ofType:@"plist"];
	NSArray *array = [NSArray arrayWithContentsOfFile:file];
	NSLog(@"%@", array);

var file = NSBundle.mainBundle().pathForResource("Data", ofType: "plist");

var array = NSArray(contentsOfFile: "file")

println(array)

Output

2014-01-27 19:53:51.555 array[25037] ( Eezy , Tutorials )

+ arrayWithContentsOfURL:

Creates and returns an array containing the contents specified by a given URL.

Example

			
		NSURL *url = [NSURL URLWithString:@"http://ios.eezytutorials.com/sample-files/sample-array-plist.plist"];
		NSArray *array = [NSArray arrayWithContentsOfURL:url];
		NSLog(@"%@",array ]);

var url = NSURL(string: "http://ios.eezytutorials.com/sample-files/sample-array-plist.plist")

var array = NSArray(contentsOfURL: url!)

println(array)

Output

2014-01-27 19:53:51.555 array[25037] ( Eezy , Tutorials )

+ arrayWithObjects:count:

Creates and returns an array that includes a given number of objects from a given C array.

Example

			NSString *values[3];
			values[0] = @"Eezy";
			values[1] = @"Tutorials";
			values[2] = @"Website"; // Website ignored since count is 2 
			NSArray *array = [NSArray arrayWithObjects:values count:2];
			NSLog(@"%@",array ]);

// Implementation in progress

Output

			2014-01-27 19:53:51.555 array[25037] ( Eezy , Tutorials )

Initializing an Array

- init

Initializes a newly allocated array. Recommended use is [NSArray array] instead of [[NSArray alloc]init]

Example

			NSArray *array = [[NSArray alloc]init];
			NSLog(@"%@",array ]);

var array = NSArray.init()
     
print(array)

Output

2014-01-27 19:53:51.555 array[25037] ( )

- initWithArray:

Initializes a newly allocated array by placing in it the objects contained in a given array. Recommended use is [NSArray arrayWithArray:] instead of [[NSArray alloc]initWithArray:]

Example

var tempArray:NSArray = NSArray(array: ["Eezy","Tutorials"])
 
var array = NSArray(array: tempArray)
 
println(array)

var array = NSArray()
     
print(array)

Output

2014-01-27 19:53:51.555 array[25037] ( Eezy , Tutorials )

- initWithArray:copyItems:

Initializes a newly allocated array using anArray as the source of data objects for the array.

Example

			NSArray *tempArray = [NSArray arrayWithObjects:@"Eezy",@"Tutorials"];
			// Check if the two array objects refer to same objects. It shouldn't.
			NSArray *array =  [[NSArray alloc]initWithArray:tempArray copyItems:YES];	
			NSLog(@"%@",array);

	// implementation in progress

Output

2014-01-27 19:53:51.555 array[25037] ( Eezy , Tutorials )

- initWithContentsOfFile:

Initializes a newly allocated array with the contents of the file specified by a given path. Recommended use is [NSArray arrayWithContentsOfFile:] instead of [[NSArray alloc]initWithContentsOfFile:]

Assuming we have the following data in plist in application bundle that is the plist is added to our project.

		<?xml version="1.0" encoding="UTF-8"?>
		<!DOCTYPE plist PUBLIC "-//Apple//DTD PLIST 1.0//EN" "http://www.apple.com/DTDs/PropertyList-1.0.dtd">
		<plist version="1.0">
		 <array>
			<string>Eezy</string>
			<string>Tutorials</string>
		</array>
		</plist>

Example

		NSString *file = [[NSBundle mainBundle] pathForResource:@"Data" ofType:@"plist"];
		NSArray *array = [[NSArray alloc]initWithContentsOfFile:file];
		NSLog(@"%@", array);

var file = NSBundle.mainBundle().pathForResource("Data", ofType: "plist");

var array = NSArray(contentsOfFile: "file")

println(array)

Output

2014-01-27 19:53:51.555 array[25037] ( Eezy , Tutorials )

- initWithContentsOfURL:

Initializes a newly allocated array with the contents of the location specified by a given URL. Recommended use is [NSArray arrayWithContentsOfURL:] instead of [[NSArray alloc]initWithContentsOfURL:]

Example

		NSURL *url = [NSURL URLWithString:@"http://ios.eezytutorials.com/sample-files/sample-array-plist.plist"];
		NSArray *array = [[NSArray alloc]initWithContentsOfURL:url];
		NSLog(@"%@",array ]);

var url = NSURL(string: "http://ios.eezytutorials.com/sample-files/sample-array-plist.plist")

var array = NSArray(contentsOfURL: url!)

println(array)

Output

			2014-01-27 19:53:51.555 array[25037] ( Eezy , Tutorials )

- initWithObjects:

Initializes a newly allocated array by placing in it the objects in the argument list. Recommended use is [NSArray arrayWithObjects:] instead of [[NSArray alloc]initWithObjects:]

Example

			NSArray *array =  [[NSArray alloc] initWithObjects:@"Eezy",@"Tutorials"];		
			NSLog(@"%@",array)

		// implementation in progress

Output

2014-01-27 19:53:51.555 array[25037] ( Eezy , Tutorials )

- initWithObjects:count:

Initializes a newly allocated array to include a given number of objects from a given C array. Recommended use is [NSArray arrayWithObjects:count:] instead of [[NSArray alloc]initWithObjects:count:]

Example

			NSString *values[3];
			values[0] = @"Eezy";
			values[1] = @"Tutorials";
			values[2] = @"Website"; // Website ignored since count is 2 
			NSArray *array = [[NSArray alloc] initWithObjects:values count:2];
			NSLog(@"%@",array ]);

		// implementation in progress

Output

2014-01-27 19:53:51.555 array[25037] ( Eezy , Tutorials )

Querying an Array

- containsObject:

Returns a Boolean value that indicates whether a given object is present in the array.

Example

			NSArray *array =  [NSArray arrayWithObjects:@"Eezy",@"Tutorials"];		
			BOOL containsObject = [array containsObject:@"Eezy"];
			NSLog(@"Contains Object Eezy: ",containsObject)
			containsObject = [array containsObject:@"Eezy Tutorials"];
			NSLog(@"Contains Object Eezy Tutorials: ",containsObject)

var array:NSArray = NSArray(array: ["Eezy","Tutorials"])

var containsObject = array.containsObject("Eezy")
println("Contains Object Eezy: \(containsObject)")

containsObject =  array.containsObject("Eezy Tutorials")
println("Contains Object Eezy Tutorials: \(containsObject)")

Output

2014-01-27 19:53:51.555 array[25037] Contains Object Eezy: 1
2014-01-27 19:53:51.558 array[25037] Contains Object Eezy: 0

- count

Returns the number of objects currently in the array.

Example

			NSArray *array =  [NSArray arrayWithObjects:@"Eezy",@"Tutorials"];
			NSLog(@"Count: %d",[array count]);

var array:NSArray = NSArray(array: ["Eezy","Tutorials"])
println("Count: \(array.count)")

Output

2014-01-27 19:53:51.555 array[25037] Count: 2

- getObjects:range:

Copies the objects contained in the array that fall within the specified range to aBuffer.

Example

			NSArray *tempArray = [NSArray arrayWithObjects:@"Eezy",@"Tutorials", @"Website"];
			id *array;
			NSRange range = NSMakeRange(1, 2);
			objects = malloc(sizeof(id) * range.length);
			[tempArray getObjects:array range:range];
			for (index = 0; index < range.length; index++) {
				NSLog(@"Array object index %d: %@",index, objects[index]);
			}

	// Implementation in progress

Output

2014-01-27 19:53:51.555 array[25037] Array object index 0: Tutorials
2014-01-27 19:53:51.555 array[25037] Array object index 0: Website

- firstObject

Returns the first object in the array.

Example

			NSArray *array = [NSArray arrayWithObjects:@"Eezy",@"Tutorials", @"Website"];
			NSLog(@"First Object: %@", [array firstObject])

var array:NSArray = NSArray(array: ["Eezy","Tutorials"])
println("First Object: \(array.firstObject)")

Output

2014-01-27 19:53:51.555 array[25037] First Object: Eezy

- lastObject

Returns the last object in the array.

Example

			NSArray *array = [NSArray arrayWithObjects:@"Eezy",@"Tutorials", @"Website"];
			NSLog(@"Last Object: %@", [array lastObject])

var array:NSArray = NSArray(array: ["Eezy","Tutorials"])
println("Last Object: \(array.lastObject)")

Output

2014-01-27 19:53:51.555 array[25037] Last Object: Website

- objectAtIndex:

Returns the object located at the specified index.

Example

			NSArray *array = [NSArray arrayWithObjects:@"Eezy",@"Tutorials", @"Website"];
			NSLog(@"Object at index 2: %@", [array objectAtIndex:2])

var array:NSArray = NSArray(array: ["Eezy","Tutorials","Website"])
println("Object at index 2: \(array.objectAtIndex(2))")

Output

2014-01-27 19:53:51.555 array[25037] Object at index 2: Website

- objectAtIndexedSubscript:

Returns the object at the specified index. If index is beyond the end of the array (that is, if index is greater than or equal to the value returned by count), an NSRangeException is raised.

Example

			NSArray *array = [NSArray arrayWithObjects:@"Eezy",@"Tutorials", @"Website"];
			NSLog(@"Object at Indexed Subscript 2: %@", [array objectAtIndexedSubscript:2])
			NSLog(@"Object at Indexed Subscript 3: %@", [array objectAtIndexedSubscript:3])

	// Not available

Output

2014-01-27 19:53:51.555 array[25037] Object at Indexed Subscript 2: Website
2014-01-27 19:53:51.555 array[25037] Object at Indexed Subscript 3: NSRangeException: out of bounds

- objectsAtIndexes:

Returns an array containing the objects in the array at the indexes specified by a given index set.

Example

			NSArray *tempArray = [NSArray arrayWithObjects:@"Eezy",@"Tutorials", @"Website"];
			array = [tempArray objectsAtIndexes:[NSIndexSet indexSetWithIndexesInRange:NSMakeRange(1, 2)]];	
			NSLog(@"%@",array ]);

var array:NSArray = NSArray(array: ["Eezy", "Tutorials", "Website"])

println(array.objectsAtIndexes(NSIndexSet(indexesInRange: NSMakeRange(1, 2))))

Output

2014-01-27 19:53:51.555 array[25037] ( Tutorials , Website )

- objectEnumerator

Returns an enumerator object that lets you access each object in the array. You can use Fast enumeration that is for in statement instead

Example

			NSArray *array = [NSArray arrayWithObjects:@"Eezy",@"Tutorials", @"Website"];
			NSEnumerator *enumerator = [array objectEnumerator];
			id anObject;
			while (anObject = [enumerator nextObject]) {
				NSLog(@"%@",anObject ]);
			}

var array:NSArray = NSArray(array: ["Eezy", "Tutorials", "Website"])

var enumerator = array.objectEnumerator()

var anObject:NSString?
anObject = enumerator.nextObject() as? NSString

while(anObject != nil){
   println(anObject)
   anObject = enumerator.nextObject() as? NSString
}

Output

2014-01-27 19:53:51.555 array[25037] Eezy
2014-01-27 19:53:51.555 array[25037] Tutorials 
2014-01-27 19:53:51.555 array[25037] Website

- reverseObjectEnumerator

Returns an enumerator object that lets you access each object in the array, in reverse order.

Example

			NSArray *array = [NSArray arrayWithObjects:@"Eezy",@"Tutorials", @"Website"];
			NSEnumerator *enumerator = [array reverseObjectEnumerator];
			id anObject;
			while (anObject = [enumerator nextObject]) {
				NSLog(@"%@",anObject ]);
			}

var array:NSArray = NSArray(array: ["Eezy", "Tutorials", "Website"])

var enumerator = array.reverseObjectEnumerator()

var anObject:NSString?
anObject = enumerator.nextObject() as? NSString

while(anObject != nil){
   println(anObject)
   anObject = enumerator.nextObject() as? NSString
}

Output

2014-01-27 19:53:51.555 array[25037] Website
2014-01-27 19:53:51.555 array[25037] Tutorials 
2014-01-27 19:53:51.555 array[25037] Eezy

Finding Objects in an Array

- indexOfObject:

Returns the lowest index whose corresponding array value is equal to a given object. If none of the objects in the array is identical to anObject, returns NSNotFound.

Example

			NSArray *array = [NSArray arrayWithObjects:@"Eezy",@"Tutorials", @"Website"];
			NSLog(@"Index of Website is %d",[array indexOfObject:@"Website"]);

var array:NSArray = NSArray(array: ["Eezy", "Tutorials", "Website"])

var index = array.indexOfObject("Website")

println("Index of Website is \(index)");

Output

2014-01-27 19:53:51.555 array[25037] Index of Website is 2

- indexOfObject:inRange:

Returns the lowest index within a specified range whose corresponding array value is equal to a given object. If none of the objects in the array is identical to anObject, returns NSNotFound.

Example

			NSArray *array = [NSArray arrayWithObjects:@"Eezy",@"Tutorials", @"Website",@"Eezy"];
			NSRange range = NSMakeRange(1, 2);
			NSLog(@"Index of Eezy in range 1,3 is %d",[array indexOfObject:@"Eezy" inRange:range ]);
			range = NSMakeRange(0, 3);
			NSLog(@"Index of Eezy in range 0,3 is %d",[array indexOfObject:@"Eezy" inRange:range ]);

var array:NSArray = NSArray(array: ["Eezy", "Tutorials", "Website", "Eezy"])

var range = NSMakeRange(1, 3);
var index = array.indexOfObject("Eezy", inRange: range)
println("Index of Eezy in range 1,3 is \(index)")
range = NSMakeRange(0, 3)
index = array.indexOfObject("Eezy", inRange: range)

println("Index of Eezy in range 1,3 is \(index)")

Output

2014-01-27 19:53:51.555 array[25037] Index of Eezy in range 1,3 is 3
2014-01-27 19:53:51.555 array[25037] Index of Eezy in range 0,3 is 0

- indexOfObjectIdenticalTo:

Returns the lowest index whose corresponding array value is identical to a given object. It checks for same memory address. This is used to compare two array sharing some objects.If none of the objects in the array is identical to anObject, returns NSNotFound.

Example

			NSString *str = @"Eezy";
			NSArray *array = [NSArray arrayWithObjects:str,@"Tutorials", @"Website"];
			NSLog(@"Index of Eezy identical",[array indexOfObject:str]);
			NSLog(@"Index of Eezy identical",[array indexOfObject:@"Eezy"]);

	// Implementation in progress

Output

2014-01-27 19:53:51.555 array[25037] Index of Eezy identical is 3
2014-01-27 19:53:51.555 array[25037] Index of Eezy identical is 2147483647 // NSNotFound

- indexOfObjectIdenticalTo:inRange:

Returns the lowest index within a specified range whose corresponding array value is equal to a given object .

Example

			NSString *str = @"Eezy";
			NSArray *array = [NSArray arrayWithObjects:@"Eezy",@"Tutorials", @"Website", str];
			NSRange range = NSMakeRange(1, 3);
			NSLog(@"Index of Eezy identical",[array indexOfObject:str inRange:range ]);
			range = NSMakeRange(0, 3);
			NSLog(@"Index of Eezy identical",[array indexOfObject:str inRange:range ]);

	// Implementation in progress

Output

2014-01-27 19:53:51.555 array[25037] Index of Eezy identical in range 1,3 is 3
2014-01-27 19:53:51.555 array[25037] Index of Eezy identical in range 0,3 is 2147483647 // NSNotFound

- indexOfObjectPassingTest:

Returns the index of the first object in the array that passes a test in a given Block.

Example

			NSArray *array = [NSArray arrayWithObjects:@"Eezy",@"Tutorials", @"Website"];

			int index = [array indexOfObjectPassingTest:^BOOL(id element,NSUInteger idx,BOOL *stop){
				 return [(NSArray *)element containsObject:@"Eezy"];
			}];
			NSLog(@"Index is %d",index);
		    if (index >= 0 && index < [arrayWithArray count]){
				[arrayWithArray removeObjectAtIndex:index];
			}

	// Implementation in progress

Output

2014-01-27 19:53:51.555 array[25037] Index is 0

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