Can you cast an NSString to an NSInterger? if the String contains numbers only?

Question

I have some numbers stored in an NSString.

Is it safe to extract them into an NSInterger like this :

NSString* path = [[NSBundle mainBundle] pathForResource:@"rugby" ofType:@"txt" inDirectory:@""];
NSString* data = [NSString stringWithContentsOfFile:path encoding: NSUTF8StringEncoding error: NULL];
NSMutableArray *statsHolder = [[NSMutableArray alloc] init];

[statsHolder addObject:[NSString [data substringWithRange:NSMakeRange(0, 3)] integerValue]];

Am i misunderstanding how to do this or would that be valid?

My second question is about objects. I am trying to copy objects. I am worried that if i copy an object into an array then later change the value contained in the object that was copied into the array, the object thats in the array will also have the value changed as it is just a pointer to the original object. I demo what i mean in code as its hard to make clear.

    else if ([newString isEqualToString: newline])
    {
        [statsHolder addObject:[[data substringWithRange:NSMakeRange(i-rangeCount, rangeCount)] integerValue]]; 
        commaCount=0;
        rangeCount=0;
        Card  *myCard = [[Card alloc] init];
        myCard.name = nameHolder;
        myCard.information = infoHolder;
        for (int x = 0; x < [statsHolder count]; x++)
             {
                 [myCard.statsArray addObject:[statsHolder objectAtIndex:x]];   
             }

        [deckArray addObject:myCard];       
        [myCard autorelease];
        [statsHolder removeAllObjects];

    }

You can see above I am filling an object called Card *mycard and then copying this into my NSMutableArray *deckArray.

NSString *nameHolder = @"";
NSString *infoHolder = @"";
NSMutableArray *statsHolder = [[NSMutableArray alloc] init];

Are my vars to hold the data while i collect it, before there is enough to populate the Card object and copy it into the array.

So my question is.. Will my all the Card objects stored in the array all point to the last values that were contained in

NSString *nameHolder = @"";
NSString *infoHolder = @"";
NSMutableArray *statsHolder = [[NSMutableArray alloc] init];

Because of the way arrays and pointers work?

Sorry for asking a big complicated question. :)

-Code

Answer 1

1. Yes, to convert an NSString to NSInteger, -integerValue is the correct way. However, an NSInteger is not an Objective-C object type. Therefore, it cannot be stored inside an NSArray. You have to box the integer by an NSNumber, i.e.

   NSInteger theValue = [[data substringWithRange:NSMakeRange(0,3)] integerValue];
   NSNumber* boxedValue = [NSNumber numberWithInteger:theValue];
   [statsHolder addObject:theValue];
   

Answer 2

Just use the [NSString integerValue] property to get the int value from a string. You can then store that in a variable like TheValue and put that into your array as an int or a NSNumber. I'm not sure if an NSInteger can go into an array unless it's in an NSDictionary.

Answer 3

The integerValue method is a perfectly fine way to convert a string to an integer. Another way, especially if you plan on storing multiple ints in a string (perhaps separated by a comma), is NSScanner.

NSScanner *scanner = [NSScanner scannerWithString:someString];

NSInteger number1, number2;

[scanner scanInteger:&number1];            // Copy the first int
[scanner scanString:@"," intoString:NULL]; // Skip the comma
[scanner scanInteger:&number2];            // Copy the second int

You need to wrap your number in some kind of object before putting it into an array. NSNumber is designed for this:

[myArray addObject:[NSNumber numberWithInteger:number1]];

Finally, what happens when you set properties on your Card class depends on how you declared the properties or wrote the methods. When it comes to strings, it’s usually a good idea to copy them:

@interface Card : NSObject
{
// …
}
@property (nonatomic, copy) NSString *name;
@end

Now, when you card.name = xyz, the card will store a copy of xyz. If the original is modified or released, it won’t affect your card’s copy of the string.