Question

I need to copy the contents of an NSArray to NSMutable array. In other words, I want to copy arrayCountryChoices to arraySearchResults. Any ideas????

//main data
NSArray *arrayCountryChoices;

//search results buffer 
NSMutableArray *arraySearchResults;


//create data 
arrayCountryChoices = [[NSArray alloc] initWithObjects:@"foo",@"bar",@"baz",nil];   

//copy the original array to searchable array ->> THIS  IS NOT WORKING AS EXPECTED
arraySearchResults = [[NSMutableArray alloc] arrayWithArray:arrayCountryChoices];

Thanks in advance.

Answer 1

it’s either

[NSMutableArray arrayWithArray:anArray];

or

[[NSMutableArray alloc] initWithArray:anArray];

or

[anArray mutableCopy];

The code in your example doesn’t work because you’re calling arrayWithArray on an instance of NSMutableArray, but arrayWithArray is a class method.

As a general rule, initalization methods that start with init are instance methods, and those that start with the name of the class (array, etc.) are class methods. Class methods return autoreleased objects, while instance methods return retained objects.