Object removal from NSMutableArray - nsmutablearray

Question

I am having some problem working with "removeObjectAtIndex" method in order to remove some a certain type of string literal in a mutable array, using the following technique (I wrote this in a text editor):-
#import <Foundation/Foundation.h>
#interface Test: NSObject
#property NSMutableArray *elements;
-(void) method;
#end
#implementation Test
#synthesize elements;
-(void) method{
elements= [[NSMutableArray alloc] init];
[elements addObjectsFromArray:#[#"c", #"a", #"b", #"c", #"c", #"d", #"c", #"c", #"e", #"c"]];
NSLog(#"number of elements initially- %d", elements.count);
int index= elements.count-1;
for(id i in [elements reverseObjectEnumerator])
{
// static int index= elements.count-1;
NSLog(#"index- %d", index);
if([i isEqual:#"c"]){
[elements removeObjectAtIndex:index];
NSLog(#"Object in place of removed object- %#, at index- %d", [elements objectAtIndex:index], index);
NSLog(#"No. of elements left after the removal- %d", elements.count);
}
index--;
}
}
#end
int main()
{
Test *test= [[Test alloc] init];
[test method];
NSLog(#"elements- %#", test.elements);
}
On running this in the terminal, I get an out of bounds exception.
cd '~/Desktop/Source Code/'; clang -framework Foundation -w ObjectRemovalInArray.m -o ~/Desktop/Binaries/ObjectRemovalInArray && ~/Desktop/Binaries/ObjectRemovalInArray
2018-06-18 20:25:25.797 ObjectRemovalInArray[4684:731973] number of elements initially- 10
2018-06-18 20:25:25.797 ObjectRemovalInArray[4684:731973] index- 9
2018-06-18 20:25:25.798 ObjectRemovalInArray[4684:731973] *** Terminating app due to uncaught exception 'NSRangeException', reason: '*** -[__NSArrayM objectAtIndex:]: index 9 beyond bounds [0 .. 8]'
*** First throw call stack:
(
0 CoreFoundation 0x00007fff345f632b __exceptionPreprocess + 171
1 libobjc.A.dylib 0x00007fff5b764c76 objc_exception_throw + 48
2 CoreFoundation 0x00007fff34637634 _CFThrowFormattedException + 202
3 CoreFoundation 0x00007fff34515290 __CFStringDecodeByteStream3 + 0
4 ObjectRemovalInArray 0x00000001007dbbaf -[Test method] + 799
5 ObjectRemovalInArray 0x00000001007dbd54 main + 68
6 libdyld.dylib 0x00007fff5c37e015 start + 1
7 ??? 0x0000000000000001 0x0 + 1
)
libc++abi.dylib: terminating with uncaught exception of type NSException
Abort trap: 6
Bascially, i kind of understand this problem by realizing that in the beginning of the loop, I'm having the "i" (of type id) pointer point to the last object in the array which also happens to be the object that is up for deletion. And when that happens, the mutable-array shrinks by 1 memory location leaving the 10th one (index-9) inaccessible as it becomes deallocated. So by then the "i" pointer needed to have moved a spot back to the next object, but that doesn't happen under the hood. Should I fix this using a sentinel of sorts in the end? Because did try using "nil" by putting it at the end of the array. But it wouldn't take in (void *)object. How do I fix this? Any assist would be of much help to me. Please note that I want to solve the problem using fast-enumeration only.
Strangely, the problem doesn't arise inside Xcode. I have used the same code snippet there; built and run it as a part of a larger project. No issues there. No exceptions thrown then.