Objective C Compiler Errors

Question

I am new to objective C. I am writing code for a coding competition. For that, I am writing code in my XCode IDE and I upload the code on their website. The code that works in my machine gives compiler errors on the website.

For e.g. A simple assignment of array element which works for me in XCode.

NSArray *itemArray;
NSString *feet;
feet = itemArray[0];

The above line generates error "incompatible types when assigning to type 'struct NSString *' from type 'struct NSArray'"

I have to use the following syntax to make it work.

feet = [itemArray objectAtIndex:0];

Similary, the for loop.

for (int i = 0; i <= count - 1; i++) {
<#statements#>
}

This gives error "for loop initial declarations are only allowed in C99 or C11 mode". I need to make the following change to make it work.

int i;
for (i = 0; i <= count - 1; i++) {
<#statements#>
}

Could anyone please advise how do I configure my XCode IDE so that I can write the code compatible with the compiler in the website?

Apparently, the supported version of Objective C on the website is GCC 4.4.5 I would like to know whether I can configure it in XCode

@NitinGohel I tried to change "C Language Dialect" in the build settings. There are options like ANSI C, C89, GNU89, C99 and GNU 99. ANSI C and C89 gives a lot of compiler errors including errors in header files. Other options work fine. — C B
– C B, Commented Apr 26, 2016 at 9:41

Niko · Accepted Answer · 2016-04-26 07:48:25Z

0

On your first exemple, you are just declaring your variables, but you need to create an instance for you array and fill it with some elements.

NSArray *itemArray = @[@"item1-String", @"item2-String"];
NSString *feet = itemArray[0];

Otherwise trying to get the first element of the array (with itemArray[0] or [itemArray objectAtIndex:0] will result in an issue because the array is not instanciated.

Note that if your array is meant tot by dynamic (add/remove elements later), use a NSMutableArray type

 NSMutableArray *itemArray = [@[@"item1-String", @"item2-String"] mutablecopy];

And if you don't know how many items contains your array, check its count before trying to get element :

NSString *feet;
if (itemArray.count <= 3) { //Is there at least 3 elements? 
    feet = itemArray[2]; //then get third element
}

answered Apr 26, 2016 at 7:48

Niko

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3 Comments

C B Over a year ago

I left out a lot of code from my post as I just wanted to highlight the problem. I just want to know why itemArray[0] is giving compiler error.

Niko Over a year ago

What is then the type of the first item in your array ?

C B Over a year ago

My array contains strings. It is initialized as NSArray *itemArray = @[@"A", @"B", @"C", @"D"];

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