Question

I have got a problem with converting an NSNumber value to an NSString

MyPowerOnOrNot is an NSNumber witch can only return a 1 or 0
and myString is an NSString..

myString = [NSString stringWithFormat:@"%d", [myPowerOnOrNot stringValue]];

NSLog(@"%@",myString);
if(myString == @"1") {
    [tablearrayPOWERSTATUS addObject:[NSString stringWithFormat:@"%@",@"ON"]];
}
else if(myString == @"0") {
    [tablearrayPOWERSTATUS addObject:[NSString stringWithFormat:@"%@",@"OFF"]];
}

What is wrong with this?

The NSLog shows 0 or 1 in the console as a string but I can’t check it if it is 1 or 0 in an if statement?

If doesn’t jump into the statements when it actually should.. I really don’t understand why this doesn’t works..
Any help would be very nice!

Answer 1

A couple of problems

myString = [NSString stringWithFormat:@"%d", [myPowerOnOrNot stringValue]];

-stringValue sent to an NSNumber gives you a reference to a string. The format specifier %d is for the C int type. What would happen in this case is that myString would contain the address of the NSString returned by [myPowerOnOrNot stringValue]. Or, on 64 bit, it would return half of that address. You could actually use [myPowerOnOrNot stringValue] directly and avoid the relatively expensive -stringWithFormat:

if(myString == @"1")

myString and @"1" are not necessarily the same object. Your condition only checks that the references are identical. In general with Objective-C you should use -isEqual: for equality of objects, but as we know these are strings, you can use -isEqualToString:

if ([[myPowerOnOrNot stringValue] isEqualToString: @"1"])

Or even better, do a numeric comparison of your NSNumber converted to an int.

if ([myPowerOnOrNot intValue] == 1)

Finally if myPowerOnOrNot is not supposed to have any value other than 0 or 1, consider having a catchall else that asserts or throws an exception just in case myPowerOnOrNot accidentally gets set wrong by a bug.