NSMutableArray not working at all

问题

I'm trying to add sprites to a NSMutableArray but it's not adding them. This is what I have:

NSMutableArray *tail;
CCSprite *block;
int j;
-(void)handleTail:(CCSprite*)pos{
    CGPoint point= pos.position;
    block = [CCSprite spriteWithFile:@"Icon-Small-50.png"];
    //Adding the tail blocks
    block.scale = .8;
    block.color = ccGREEN;
    block.position = point;
    NSLog(@"Block Pos (%f,%f)",block.position.x,block.position.y);

    //CGPoint playerPos = piece.position;

    originalPos = point;

    if ([tail count] < maxLength) {
        [tileMap addChild:block];
        [tail addObject:block];
        NSLog(@"Tail length:%i",tail.count);
        j+=1;
    }
    if (j == 3) {
        NSLog(@"J called");
        [tail removeObjectAtIndex:0];
    }   
}

I don't understand why this isn't working?

回答1:

You have not alloc+inited the tail.

In awakeFromNib or init or viewDidLoad ( which ever is applicable for your class) use

tail=[[NSMutableArray alloc] init];

Suggestion NOTE : Try to follow naming convention.

As tail is an array (plural) you should use tails.

回答2:

You forget to alloc init NSMuttableArray

tail = [[NSMuttableArray alloc]init];

without alloc and init your array you cannot add object to it

when you try to access its member it returns nil

try NSLog (@"%@",tail); it returns

回答3:

You need to instantiate your NSMutableArray.

tail = [NSMutableArray array];

回答4:

You need to allocate and initialize the array.

Something like:

tail = [NSMutableArray array];

来源：https://stackoverflow.com/questions/14940873/nsmutablearray-not-working-at-all

标签

objective-c

arrays

cocos2d-iphone

nsmutablearray