Question

Hi I run into EXC_BAD_ACCESS in my code,

I’m trying to run a method in class PurchaseTowerMenuLayer,
method is from class UnitDatabase:

PurchaseTowerMenuLayer.m:

delegate = (AppDelegate *)[[UIApplication sharedApplication] delegate];
// getUnitDatabase returns UnitDatabase class from GameScene class

[[[delegate getGameScene] getUnitDatabase] createUnit:@"t01"]; //EXC_BAD_ACCESS happens here

UnitDatabase.m:

-(void)createUnit:(NSString *)unitID
{

typeString = [unitID substringWithRange:NSMakeRange(0,1)];
numberString = [unitID substringWithRange:NSMakeRange(1,2)];

Unit *unit;

if(unitID == @"t00")
    [unit setUnitID:unitID];

etc...
}

What am I doing to get this error? How should it look like?

Thanks in advance!

Answer 1

Alright, first separate the call [[[delegate getGameScene] getUnitDatabase] createUnit:@"t01"]; for three lines such as

GameScene* scene = [delegate getGameScene];
UnitDatabase* unitDatabase = [scene getUnitDatabase];
[unitDatabase createUnit:@"t01"];

This’ll allow you to pinpoint which call emits the EXC_BAD_ACCESS and you can collapse them back after if you prefer.

After you identified which line emits the error, it’s usually a matter of finding where you haven’t called [[MyClass alloc] init];. For example, if getGameScene or getUnitDatabase return objects that weren’t alloc‘d/init‘d (or delegate too for that matter), then you want to make sure to do that at least before you return them.

I can’t help much more without seeing more code but these errors often go like this. Make sure you alloc and initialize the objects you keep as members of other objects.