NSMutableArray initialization

Question

I'm very newby on Objective C. I've read a lot of topics related but couldn't get solution. I'm using a NSMutableArray, and alloc and init by the following mode:

events = [[NSMutableSet alloc] init];

Is it right? In this way, I can add objects to the array without problems, but when I iterate or to read, I got SIGABRT: unrecognized selector sent to instance. Attempting several modifications, the best I could get was another exception: EXC_BAD_ADDRESS. The line I'm using to read the array is:

Event *event = [events objectAtIndex:1];

Thanks in advance.

Junior

Hm. You are talking about NSMutableArray but do NSMutableSet alloc... ? — Dirk
– Dirk, Commented Jul 16, 2011 at 23:22

MCannon · Accepted Answer · 2011-07-16 23:37:37Z

3

you have said you are using NSMutableArrays, but then initialised a set, try using:

NSMutableArray *events = [[NSMutableArray alloc] init];

sets don't respond to objectAtIndex, because they are unordered. if you want an object out of a set, you can call anyObject on it. or you can use enumeration to go through all objects. eg

id obj=[events anyObject];

or

for(id obj in events){
    NSLog(@"%@",obj);
}

edited Jul 16, 2011 at 23:37

answered Jul 16, 2011 at 23:23

MCannon

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FeifanZ · Accepted Answer · 2011-07-16 23:21:31Z

0

What's going on in between? Remember that arrays are zero-indexed; there may not be two elements in there. Try using the count method.

answered Jul 16, 2011 at 23:21

FeifanZ

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Jules · Accepted Answer · 2011-07-16 23:23:36Z

0

events = [[NSMutableArray alloc] init];
[events addObject:event1];
[events addObject:event2]

for (int i = 0; i < [events count]; i++) {
    Event *event = (Event)[events objectAtIndex:i];
    NSLog("Event: %@", event);
    [event release];
}

Like this.

answered Jul 16, 2011 at 23:23

Jules

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1 Comment

Jules Over a year ago

You're welcome. If this solved your question, please tick it as "correct". : )

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