Changing a boolean in an NSMutableArray

Question

So I'm trying to change all the booleans in an NSMutableArray that I made which I followed from here.

i have:

@property (nonatomic, retain) NSMutableArray *isDinosaurTapped;

and synthesized:

@synthesize isDinosaurTapped;

and set up [EDITED to show isDinosaurTapped]:

NSMutableArray *newDinosaurTaps = [[NSMutableArray alloc] init];
    for( int i = 0; i < [dinoSprites count]; i++ )
    {
        NSNumber *isTapped = [posPlist valueForKeyPath:[NSString stringWithFormat:@"Dinosaurs.Dinosaur_%i.isTapped", i]];
        [newDinosaurTaps addObject:isTapped];
    }
    self.isDinosaurTapped = [newDinosaurTaps copy];


    for( int i = 0; i < [isDinosaurTapped count]; i++ )
    {
        [isDinosaurTapped replaceObjectAtIndex:i withObject:[NSNumber numberWithBool:NO]];
    }

When I build its fine, however when I actually build and run, I keep getting a SIGABRT: '-[__NSArrayI replaceObjectAtIndex:withObject:]: unrecognized selector sent to instance.

Have I set the properties of the NSMutableArray incorrectly? But according to this, my properties should be ok.

Any feedback is greatly appreciated! :D

show some lines of code where you set isDinosaurTapped. ie self.isDinosaurTapped = ... or isDinosaurTapped = ... I think it is being set to an instance of NSArray — Jesse Black
Why doesn't the compiler complain about you setting this to NSArray? It should show a yellow warning somewhere about incompatible types. — CodaFi

CodaFi CodaFi · Accepted Answer · 2012-03-08T03:38:35

You are trying to mutate an immutable array. Is it declared as NSMutableArray, or NSArray, and if it is mutable, did you call -copy, or -mutableCopy?

In core foundation, NSMutableArrays are internally known as __NSArrayM (for mutable), and NSArrays are known as __NSArrayI (for immutable).

Changing a boolean in an NSMutableArray

2 Answers