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iphoneios
iPhone Programmatically
iPhone Programmatically

Reputation: 1227

indexOfObject in an NSMutableArray returning garbage value

Trying to get index on an object in NSMutableArray. It is returning some garbage value, not getting why it is not returning index of particular item. Below is code i tried.

NSString *type = [dictRow valueForKey:@"type"];

if([arrSeatSel indexOfObject:type])
{
    NSUInteger ind = [arrSeatSel indexOfObject:type];
    [arrTotRows addObject:[arrSeatSel objectAtIndex:ind]];
}

type contains value "Gold". And arrSeatSel contains

 (
"Gold:0",
"Silver:0",
"Bronze:1"

How to check that. Please guide.

Upvotes: 0

Views: 1203

Answers (4)

Jeffery Thomas
Jeffery Thomas

Reputation: 42598

The value you are getting is NSNotFound. You are getting NSNotFound because @"Gold" is not equal to @"Gold:0".

You should try the following

NSUInteger index = [arrSeatSel indexOfObjectPassingTest:^BOOL(id obj, NSUInteger idx, BOOL *stop){
    return [obj hasPrefix:type];
}];

if (index != NSNotFound) {
    [arrTotRows addObject:[arrSeatSel objectAtIndex:index]];
}

UPDATE

-indexOfObjectPassingTest: is a running the following loop. NOTE: /* TEST */ is some code that returns true when the correct index is found.

NSUInteger index = NSNotFound;
for (NSUInteger i = 0; i < [array count]; ++i) {
   if (/* TEST */) {
       index = i;
       break;
   }
}

In my first sample, /* TEST */ is [obj hasPrefix:type]. The final for loop would look like.

NSUInteger index = NSNotFound;
for (NSUInteger i = 0; i < [arrSeatSel count]; ++i) {
   if ([arrSeatSel[i] hasPrefix:type]) {
       index = i;
       break;
   }
}

if (index != NSNotFound) {
    [arrTotRows addObject:[arrSeatSel objectAtIndex:index]];
}

I like -indexOfObjectPassingTest: better.

The [obj hasPrefix:type] part is just a different way to comparing strings. Read the -hasPrefix: doc for more details.

Hope that answers all your questions.

Upvotes: 7

Anupdas
Anupdas

Reputation: 10201

Sometimes storing data properly can solve lot of hazzle. If I guess correctly

"Gold:0" denotes a circle of type Gold an its count 0.

You can try to reformat that to an array of items.

Such as 

[
    {
        "Type": "Gold",
        "Count": 0
    },
    {
        "Type": "Silver",
        "Count": 0
    },
    {
        "Type": "Bronze",
        "Count": 1
    }
]

And then using predicate to find the index 

NSPredicate *predicate = [NSPredicate predicateWithFormat:@"Type == %@",@"Gold"];
NSUInteger index = [types indexOfObjectPassingTest:^BOOL(id obj, NSUInteger idx, BOOL *stop) {
    [predicate evaluateWithObject:obj];
}];

Upvotes: 2

Shane Hsu
Shane Hsu

Reputation: 8357

If I'm reading that correctly, you're saying that arrSeatSel contains three NSStrings, @"Gold:0", @"Silver:0", and @"Bronze:1", correct?

And then your NSString* type is basically @"Gold"

The first thing is Gold and Gold:0 are different strings, and that's just for starter.

As you are searching for a string in the array, you should take each string out, and do a string matching, not just a comparison. What I'm saying is this:

NSString* str1 = @"This is a string";
NSString* str2 = @"This is a string";
if ( str1 == str 2 ) NSLog(@"Miracle does happen!")

The conditional would never be true even though both NSStrings contain the same value, they are different object, thus are different pointers pointing to different blocks of memory.

What you should do here is a string matching, I will recommend NSString's hasPrefix: method here, as it seems to fit your need.

Upvotes: 1

Harish
Harish

Reputation: 1519

You can try doing this.

[arrSeatSel enumerateObjectsUsingBlock:^(id object, NSUInteger idx, BOOL *stop) {

    // object - will be your "type"
    // idx - will be the index of your type.
}];

hope this helps.

Upvotes: 1

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