Question

Possible Duplicate:
EXC_BAD_ACCESS when trying to get iPhone screen dimensions

I have the following code snippet in objective-c that automatically sets some variables to a number of presets. However, on the marked line I get a “Program received signal: EXC_BAD_ACCESS” exception.

What confuses me is that the line above is identical, just with a different value. If line 1 does not throw an exception, why should line 2? What can I do about this?

Thanks in advance!

Sterren

- (IBAction)presetPressed:(id)sender {
    if(self.userEnteringNumber) [self enterPressed];

    double xVal;
    double aVal;
    double bVal;
    NSString *preset = [sender currentTitle];
    if ([preset isEqualToString:@"1"]) {
        xVal = 1;
        aVal = 2;
        bVal = 3;
    } else if ([preset isEqualToString:@"2"]) {
        xVal = 1.5;
        aVal = 2.9;
        bVal = 3.0;
    } else if ([preset isEqualToString:@"3"]) {
        xVal = -1;
        aVal = -2;
        bVal = -3;
    }
    [self.variables setValue:[NSNumber numberWithDouble:xVal] forKey:@"x"];
    [self.variables setValue:[NSNumber numberWithDouble:aVal] forKey:@"a"];
    [self.variables setValue:[NSNumber numberWithDouble:bVal] forKey:@"b"];

    self.xVar.text = [NSString stringWithFormat:@"= %@", xVal];
    self.aVar.text = [NSString stringWithFormat:@"= %@", aVal]; //EXC_BAD_ACCESS here
    self.bVar.text = [NSString stringWithFormat:@"= %@", bVal];

    [self calculateResult];
}

Answer 1

xVal, aVal, bVal are all primitive doubles, but yet your string format is looking for an object via %@.

try replacing %@ with %f (or %g if you prefer scientific notation):

    self.xVar.text = [NSString stringWithFormat:@"= %f", xVal];
    self.aVar.text = [NSString stringWithFormat:@"= %f", aVal];
    self.bVar.text = [NSString stringWithFormat:@"= %f", bVal];