What is NSArray?
NSArray is Objective-C’s general-purpose array type. It represents an ordered collection of objects. NSArray is immutable, so we cannot dynamically add or remove items. Its mutable counterpart, NSMutableArray, will be discussed in the second part of this tutorial.
What is the key difference between NSArray and NSMutableArray?
NSArray and its subclass NSMutableArray manage ordered collections of objects called arrays. NSArray creates static arrays, and NSMutableArray creates dynamic arrays. You can use arrays when you need an ordered collection of objects. NSArray is “toll-free bridged” with its Core Foundation counterpart, CFArray .
What is difference between array and NSArray?
4 Answers. Array is a struct, therefore it is a value type in Swift. NSArray is an immutable Objective C class, therefore it is a reference type in Swift and it is bridged to Array> . NSMutableArray is the mutable subclass of NSArray .
How do I declare NSArray?
The NSArray class contains a class method named arrayWithObjects that can be called upon to create a new array object and initialize it with elements. For example: NSArray *myColors; myColors = [NSArray arrayWithObjects: @”Red”, @”Green”, @”Blue”, @”Yellow”, nil];
How do you make an empty NSArray?
in C I can simply declare an array like this: int array; to declare an array of size 500 which can then be filled later.
How do I know if my NSArray is empty?
NSArray has the count method, a common way to do it would be… That will check if the array has nothing in it, or if it is set to nil….
- What is the difference between (array == [NSNull null]) and (array == nil)?
- @user403015 [NSNull null] is a object of type NSNull .
What is difference between any and AnyObject in Swift?
Any can represent an instance of any type at all, including function types and optional types. AnyObject can represent an instance of any class type.
Does copy increase retain count?
No, a copied object will have a retain count of 1, just like a newly initialized object. I highly recommend you read the Memory Management Guide if you wish to learn more.
What is difference between string and NSString in Swift?
NSString : Creates objects that resides in heap and always passed by reference. String: Its a value type whenever we pass it , its passed by value. like Struct and Enum, String itself a Struct in Swift. But copy is not created when you pass.
Is Empty vs count Swift?
Defined by Apple, isEmpty is “a Boolean value indicating whether a string has no characters” and count is “the number of characters in a string”. count counts the amount of elements from index 0 to index N, so the O(N) performance. However, checking if a String isEmpty is just accessing a boolean value, then the O(1).
Is empty array Swift?
To check if an array is empty, use Swift function isEmpty on the array. Following is a quick example, to check if an array is empty. The function returns a boolean value. If the array is empty, isEmpty returns true, else false.
What is nsmutablearray and what does NSArray do?
NSArray and its subclass NSMutableArray manage ordered collections of objects called arrays. NSArray creates static arrays, and NSMutableArray creates dynamic arrays. You can use arrays when you need an ordered collection of objects. NSArray is “toll-free bridged” with its Core Foundation counterpart, CFArray.
How does the NSArray class work in Objective C?
For more information about object literals in Objective-C, see Working with Objects in Programming with Objective-C. In Swift, the NSArray class conforms to the ArrayLiteralConvertible protocol, which allows it to be initialized with array literals.
How is the length of an array calculated?
The variable len stores the length of the array. The length is calculated by finding size of array using sizeof and then dividing it by size of one element of the array.
Is the CFArray interface the same as the NSArray?
Although they are corresponding types, CFArray and NSArray do not have identical interfaces or implementations, and you can sometimes do things with CFArray that you cannot easily do with NSArray. For example, CFArray provides a set of callbacks, some of which are for implementing custom retain-release behavior.