How to create a query in NSMutableArray and print out results?

Question

I have got a NSMutableArray that is structured as follow:

{
    {
      AccountNumber:Test1
      Type: Electricity
    }

    {
      AccountNumber:Test2
      Type: Water
    }    

    {
      AccountNumber:Test3
      Type: Water
    }   
}

How to print out the account number that are in Water type?

What I have tried is as follow:

- (NSUInteger)indexOfObjectIdenticalTo:(id)data{ return data; }

But I didn't understand how to do it.

Christopher A · Accepted Answer · 2011-08-24 06:01:47Z

5

Check out NSPredicate. It will allow to you essentially define a query and apply it to your array to filter the results. This is much faster than a iterative loop through the array to find what you are looking for. For your example, you would simply need to do the following:

NSString *type = @"Water";
NSPredicate *predicate = [NSPredicate predicateWithFormat:@"Type == %@", type];
NSArray *results = [myArray filteredArrayUsingPredicate:predicate];

answered Aug 24, 2011 at 6:01

Christopher A

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jtbandes · Accepted Answer · 2011-08-24 02:31:30Z

2

Assuming each item in the array is a NSDictionary, and all the keys/values are NSStrings, you could do something like this:

for (NSDictionary *dict in myArray) {
    if ([[dict objectForKey:@"Type"] isEqualToString:@"Water"]) {
        NSLog(@"Account number %@", [dict objectForKey:@"AccountNumber"]);
    }
}

answered Aug 24, 2011 at 2:31

jtbandes

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