FILTERING NSARRAY INTO A NEW NSARRAY IN OBJECTIVE-C

Derek Honeybun

Total Post:17

Points:119
Posted by  Derek Honeybun
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I have an NSArray and I'd like to create a new NSArray with objects from the original array that meet certain criteria. The criteria is decided by a function that returns a BOOL. 

I can create an NSMutableArray, iterate through the source array and copy over the objects that the filter function accepts and then create an immutable version of it.

Is there a better way?

  1. Tarun Kumar

    Post:214

    Points:1642
    Re: filtering NSArray into a new NSArray in objective-c

    NSArray and NSMutableArray provide methods to filter array contents. NSArray provides filteredArrayUsingPredicate: which returns a new array containing objects in the receiver that match the specified predicate. NSMutableArray adds filterUsingPredicate: which evaluates the receiver’s content against the specified predicate and leaves only objects that match. These methods are illustrated in the following example.

    NSMutableArray *array = [NSMutableArray arrayWithObjects:@"Bill", @"Ben",

    @"Chris", @"Melissa", nil];

    NSPredicate *bPredicate = [NSPredicate predicateWithFormat:

    @"SELF beginswith[c] 'b'"];

    NSArray *beginWithB = [array filteredArrayUsingPredicate:bPredicate];

    // beginWithB contains { @"Bill", @"Ben" }.

    NSPredicate *sPredicate = [NSPredicate predicateWithFormat:

    @"SELF contains[c] 's'"];

    [array filterUsingPredicate:sPredicate];

    // array now contains { @"Chris", @"Melissa" }

      Modified On Aug-22-2015 02:44:31 AM

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