Getting an array of a property from an object array

Question

I need to extract an array of a single property from a custom object array. eg.

@interface MyClass : NSObject 
{
    int sampleNumber;
    NSString *sampleName;
}

I have an array of MyClass instances called myArray. I want to then get an array of the sampleName strings. Is there a way to do it without stepping through the whole array like this:

NSMutableArray *stringArray;

for (MyClass *thisInstance in myArray) 
{    
    [stringArray addObject:thisInstance.sampleName];
}

I attempted to search for a similar question in Objective-C but found it only in the PHP and LINQ sections.

I’ve fixed one typo in the declaration of MyClass: you need to declare sampleName as NSString * instead of NSString. I’ve also replaced foreach with for. — user557219
– user557219, Commented Jun 4, 2011 at 9:18
Thanks, I came back to edit it and found you had already answered :) — cone
– cone, Commented Jun 4, 2011 at 9:35

user557219 · Accepted Answer · 2011-06-04 09:16:01Z

4

Use Key-Value Coding:

NSArray *stringArray = [myArray valueForKey:@"sampleName"];

answered Jun 4, 2011 at 9:16

user557219

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1 Comment

cone Over a year ago

thanks so much @Bavarious, especially for the quick response. It took me longer to test it out than for you to answer it. I love this forum!

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