Traversing a NSMutableArray? - objective-c

Question

To start let me tell you I am a total Objective-C beginner. This is my problem:
I have a NSMutableArray that stores objects, (Player) that has the name of the player and his/her score.
I am able to add objects to the array using addObject, but I am having trouble traversing this array. This
is how I do it:
// Get the reference to the array
NSMutableArray *myarray = [delegate getArray];
// Create a numerator
NSEnumerator *e = [myarray objectEnumerator];
id object;
while (object = [e nextObject])
{
[object printPlayer];
}
The method printPlayer belongs to the Player class and it just prints the name and the score.
The problem is when I have three players in the array and I am trying to print the content, it reaches this error inside the printPlayer method:
Thread 1: EXC_BAD_ACCESS(code=1, address=0x0000008)
Strangely if I use NSLog(#"%#", object); instead of [object printPlayer]; it prints a reference to the object and does not reach any error.
Anyone could point me what could be the problem when I try to use [object printPlayer]
Cheers
Update 1:
This is my printPlayer method:
-(void) printPlayer
{
NSLog(#"\n\nName: %#\nScore: %d", playerName, playerScore);
}
Update 2:
Player.h:
#interface PROGPlayer : NSObject
#property (nonatomic, assign) NSString *playerName;
#property (nonatomic, assign) int playerScore;
-(id) init: (NSString *) n;
-(void) printPlayer;
#end
Player.m:
#import "PROGPlayer.h"
#implementation PROGPlayer
#synthesize playerName;
#synthesize playerScore;
/**
* Player's class constructor
* #param n Player's name
* #param s Player's score
*/
-init: (NSString *) n
{
if (!(self = [super init])) return nil;
else
{
playerName = n;
playerScore = 0;
}
return self;
}
-(void) printPlayer
{
NSLog(#"\n\nName: %#\nScore: %d", playerName, playerScore);
}
#end

Answer 1

It seems like your problem is in the way you're defining your properties.
You're using assign rather than strong, or copy.
In a nutshell, it's because strong implies that you want your object to be retained.
Using copy implies that you want to create a new copy of an object or a value and set that as value of your property... As Mario and Jarsen explain, using copy is better practice when working with arrays to prevent the array being mutated (i.e. values changed) while it is being enumerated / traversed. Using copy also retains the new object.
If you're using ARC and your objects are not retained, then they will be released automatically by the compiler.
Using assign means that you assume the new object has been retained elsewhere and that you don't want to retain it again.
I suppose what was happening is that you were assigning your variable to your property, but the variable was being released (and hence resulting in nil) and causing the crash.
Here are a few links:
New to Objective C: Need help understanding strong reference vs assign
Objective-C ARC: strong vs retain and weak vs assign
Clarification on assign, retain, copy, strong?

Answer 2

Your playerName property should best be copied instead of assigned
#property (nonatomic, copy) NSString *playerName;
When trying to access the assigned value, the object most likely is gone causing the bad access.
Also remember to release playerName in dealloc when you set the property to copy.
Cheers

Answer 3

You just want to enumerate the array?
for (CustomClass *object in myArray){
[object printPlayer];
}

Answer 4

Either what Mike Z said or the "crude":
for (int i = 0; i < myArray.count; i++) {
CustomClass* object = [myArray objectAtIndex:i];
[object printPlayer];
}
While there are more elegant schemes, you can clearly understand what this one is doing, and how an NS(Mutable)Array is just a simple analog to a standard C array.