Q:

Error with using local variable to access array index

For some reason this occurs every time i try to access a specific index from the array by specifying a variable int in the index in a forloop. When i do i get a Thread 1 Error, but if i use a variable that has not be declared in the forloop itself than it seem to work fine. 
Code:
for(int i =0 ; i<= [array count]; i++) {
    NSNumber *convert = [array objectAtIndex:i]; //results in error
    NSLog(@"%i", [convert intValue]);
   }

A:

Problem is you are trying to access array beyond its capacity. Array starts with 0 index and goes upto array.count - 1. That said, please try with below code and you should be good:
for (int i = 0 ; i <= array.count - 1 ; i++) {
    NSNumber *convert = [array objectAtIndex:i];
    NSLog(@"%i", [convert intValue]);
}

Another variation could be:
for (int i = 0 ; i < array.count ; i++) {
    NSNumber *convert = [array objectAtIndex:i];
    NSLog(@"%i", [convert intValue]);
}

