将NSArray复制到成员变量

Question

I have a setter in my class:

-(void)setNumbers:(NSArray *)aNumbers{
  NSArray *tArray = [[NSArray alloc]initWithArray:aNumbers]; //throws BAD ACCESS
  self.numbers = tArray;
  //also tried self.numbers = [tArray copy];
  [tArray release];

}

If I invoke the setter like this:

NSArray *numbers = [TicketManager getRandomNumbersFor:@"LottoNormal"];
[self.ticket setNumbers:numbers];

In the 'getRandomNumbersFor:' method (the loop gets executed):

+(NSArray *)getRandomNumbersFor:(NSString *)aTicketType{

  NSLog(@"getting RandomNumbers for: %@",aTicketType);
  NSMutableArray *tResult;
  if([aTicketType isEqualToString:@"LottoNormal"]){
    tResult = [NSMutableArray arrayWithCapacity:6];
    for(int i = 0;i<6;i++){
        int tNumber = arc4random() % 48;
        tNumber++;
        NSLog(@"Number: %i",tNumber);
        [tResult addObject:[NSNumber numberWithInt:tNumber]];
    }
  }

  return tResult;
}

In a ViewController I´m getting a bad access in the marked line.
Can anyone can help?

Answer 1

By the way, why have you written the setNumbers setter method? Given that you defined a property, numbers , a setter method called setNumbers will be synthesized for you. Worse, your setNumbers calls itself! The construct

self.numbers = tArray;

is equivalent to calling

[self setNumbers:tArray];

That results in infinite recursion.

As an aside, I'd advise against writing your own setNumbers setter method unless there is a compelling reason to do so. The default setter does all sorts of wonderful stuff (appropriate memory management, KVO, etc.), so you should think long and hard about replacing it with your own. Just let the compiler synthesize your accessor methods (setters and getters) for you, if you can.

If you have to write your own accessor methods for some reason, at the very least, make sure to reference instance variables, not accessor methods.

Answer 2

How is self.numbers defined? You may not need to make your own setter here.

Rather than

@property (nonatomic, retain) NSArray *numbers;

you could declare is as copied:

@property (nonatomic, copy) NSArray *numbers;

And let the dynamic setter do the copy work for you. This'll also handle an incoming nil.