I'm having problems with converting
NSString *stringValue = @"9.2";
NSNumberFormatter *formatter = [[NSNumberFormatter alloc] init];
NSLog(@"stringvalue:%@",[[formatter numberFromString: stringValue] stringValue]);
You are discovering that floating point numbers can't always be represented exactly. There are numerous posts about such issues.
If you need to get back to the original string, then keep the original string as your data and only convert to a number when you need to perform a calculation.
You may want to look into
NSDecimalNumber. This may better fit your needs.
NSString *numStr = @"9.2"; NSDecimalNumber *decNum = [NSDecimalNumber decimalNumberWithString:numStr]; NSString *newStr = [decNum stringValue]; NSLog(@"decNum = %@, newStr = %@", decNum, newStr);
9.2 for both values.