CODEWITHSUNDEEP
iosobjective-cnsarray
Nurdin
Nurdin

Reputation: 23883

addObject to NSArray in Objective-C

How to addObject to NSArray using this code? I got this error message when trying to do it.

NSArray *shoppingList = @[@"Eggs", @"Milk"];
NSString *flour = @"Flour";
[shoppingList addObject:flour];
shoppingList += @["Baking Powder"]

Error message

/Users/xxxxx/Documents/iOS/xxxxx/main.m:54:23: No visible @interface for 'NSArray' declares the selector 'addObject:'

Upvotes: 6

Views: 25546

Answers (4)

Claudio Redi
Claudio Redi

Reputation: 68400

Your array cant be changed because is defined as NSArray which is inmutable (you can't add or remove elements) Convert it to a NSMutableArray using this 

NSMutableArray *mutableShoppingList = [NSMutableArray  arrayWithArray:shoppingList];

Then you can do 

[mutableShoppingList addObject:flour];

Upvotes: 2

Kirti Nikam
Kirti Nikam

Reputation: 2206

NSArray does not have addObject: method, for this you have to use NSMutableArray. NSMutableArray is used to create dynamic array.

NSArray *shoppingList = @[@"Eggs", @"Milk"];
NSString *flour = @"Flour";

NSMutableArray *mutableShoppingList = [NSMutableArray arrayWithArray: shoppingList];
[mutableShoppingList addObject:flour];

Or

NSMutableArray *shoppingList = [NSMutableArray arrayWithObjects:@"Eggs", @"Milk",nil];
NSString *flour = @"Flour";
[shoppingList addObject:flour];

Upvotes: 1

Sergey Kalinichenko
Sergey Kalinichenko

Reputation: 726579

addObject works on NSMutableArray, not on NSArray, which is immutable.

If you have control over the array that you create, make shoppingList NSMutableArray:

NSMutableArray *shoppingList = [@[@"Eggs", @"Milk"] mutableCopy];
[shoppingList addObject:flour]; // Works with NSMutableArray

Otherwise, use less efficient

shoppingList = [shoppingList arrayByAddingObject:flour]; // Makes a copy

Upvotes: 19

marhs08
marhs08

Reputation: 67

You can't add objects into NSArray. Use NSMutableArray instead :)

Upvotes: 4

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