[__NSArrayM objectAtIndex:]: index 2 beyond bounds for empty array

Question

I get the error:

*** Terminating app due to uncaught exception 'NSRangeException', reason: '*** -[__NSA

Here is my code:

static NSArray * clone(NSArray * a, NSUInteger b)
{
    // return a.slice(b);
    return [a subarrayWithRange:NSMakeRange(b, a.count - b)];
}
// swap: function(a, b) {
static NSArray * swap(NSArray *a, NSUInteger b)
{
    NSMutableArray * array = [NSMutableArray arrayWithArray:a];

// var t1, t2;
id t1, t2;

// t1 = a[0];
t1 = array.firstObject;

// t2 = a[b % a.length];
t2 = array[b % a.count];

// a[0] = t2;
array[1] = t2;

// a[b] = t1;
array[b] = t1;

// return a;
return array.copy;
}

I'm confused on why it is giving me the error. This is just a snippet of the code, This comes from a modified version of HCYoutubeParser.

Read the error. The array is empty. You can't access elements of an empty array. Point out the exact line causing the error. Use the debugger to step through the code and determine why the array is empty. — rmaddy
– rmaddy, Commented Feb 17, 2015 at 15:03
it throws here: t2 = array[b % a.count]; It returns with 0 objects, so it throws. How do i make it skip over certain parts of code if it has 0 objects — Robert Myers
– Robert Myers, Commented Feb 17, 2015 at 15:19
That means that array is empty which means that the a array is empty. Find where you call swap and see why you pass in an empty array. Better yet, fix your swap function so it handles arrays with any number of elements. — rmaddy
– rmaddy, Commented Feb 17, 2015 at 15:25
im using this: raw.githubusercontent.com/samnung/YPlayer/… — Robert Myers
– Robert Myers, Commented Feb 17, 2015 at 15:26
How do I change the swap function for this? kinda a noobs sorry. — Robert Myers
– Robert Myers, Commented Feb 17, 2015 at 15:27

user1453351 · Accepted Answer · 2015-02-17 14:43:40Z

3

Because simply if you debug your application, you'll find that in this line

array[1] = t2;

The variable array doesn't have 2 items to access the item #1, it contains either 0 or 1 item, you should do a check like this

if (array.count >= 2) {
    array[1] = t2;
}

answered Feb 17, 2015 at 14:43

user1453351

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9 Comments

Robert Myers Over a year ago

So it brings back a error that there are 0 objects, and it crashes. heres the link to the code im using: raw.githubusercontent.com/samnung/YPlayer/…

user1453351 Over a year ago

Actually I guess the code is good because I can't see any access to the second item of the array, array[1] go and search for it

Robert Myers Over a year ago

search for an array? I don't know what to do:( It throws because there is 0 objects, could i make it go to another file if there are 0 objects?

user1453351 Over a year ago

Simply make the check, if (array.count > 0) {

Robert Myers Over a year ago

But how do i link it to go to another file?

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