Question

There are lots of examples on this site about adding to NSMutableArray and I have looked at many but I still don’t either understand (highly possible) or am missing something fundamental.

I am trying to add to an NSMutableArray via a for loop. I want to keep track of button x,y coordinate position using the button tag as key/index so I can change a button as a user clicks it. This is all without IB.

My init is as follow:

self.tmpXpos = [[NSMutableArray alloc] init];
self.tmpYpos = [[NSMutableArray alloc] init];

[self.tmpXpos insertObject:[NSNull null] atIndex:0];

[self.tmpYpos insertObject:[NSNull null] atIndex:0];
**I added these after reading about ‘creating’ the array and populating it with null.

In the loop:

NSUInteger btag = button.tag; //NSUInterger as per help

>>NSNumber *xNumber = [NSNumber numberWithInteger:[self xpos]]; // NSNumber as an Object wrapper
>>NSNumber *yNumber = [NSNumber numberWithInteger:[self ypos]];


>>[self.tmpXpos insertObject:xNumber atIndex:btag];
>>[self.tmpYpos insertObject:yNumber atIndex:btag];

NSLog(@”%d, %@, %@”,btag,xNumber,yNumber);

The log entries look ok:

2,64,0

3,128,0

etc for each button to be added to the screen.

During debugging – the tmpXpos and tmpYpos listed as ” 0 Objects ” under self.

I retrieve the information thusly:

NSUInteger tmpSt = [self.sTags integerValue];

NSNumber *tmpX = [self.tmpXpos objectAtIndex:tmpSt];

NSNumber *tmpY = [self.tmpYpos objectAtIndex:tmpSt];

int tmpPositionX = [tmpX intValue];

int tmpPositionY = [tmpY intValue];

NSLog(@”%d, %d”,tmpPositionX, tmpPositionY);

NSLog yields 0, 0

I do appreciate any guidance or questions you folks might have as this site’s ‘sanity checks’ have saved my bacon in the past.

I am ignoring memory leaks as of yet, but they are in the back of my mind. No worries there.
Ironically, I have a couple of other arrays that work just fine, but the exception is that they are not populated via a loop.

Lastly, the code works fine as the button at location 0,0 does change as per design, LOL, but not for any other location.

Thanks again!

Neil

Answer 1

I think your problem is that you are creating the NSNumbers with the method numberWithInteger, when an NSUInteger is actually an unsigned long. So try

xNumber = [NSNumber numberWithUnsignedLong:[self xpos]];