Three options how to validate `NSString` instance to contain numeric value.

Validate NSString as number

NSString *theString; // You have a string.



/// Option 1: floatValue
if ([theString floatValue] != 0 || [theString hasPrefix:@"0.0"] || [theString isEqualToString:@"0"]) {
    // theString should be number
}



/// Option 2: NSRegularExpression
NSRegularExpression *regexNumber = [NSRegularExpression regularExpressionWithPattern:@"^[-+]?[0-9]*\\.?[0-9]+$"
                                                                            options:0
                                                                              error:nil];
NSUInteger matches = [regexNumber numberOfMatchesInString:theString
                                                  options:0
                                                    range:NSMakeRange(0, theString.count)];
// in this case only zero or one match is possible, since the regex contains ^...$
if (matches > 0) {
    // theString is number
}



/// Option 3: NSDecimalNumber
NSDecimalNumber *decimalNumber = [NSDecimalNumber decimalNumberWithString:theString
                                                                   locale:[NSLocale currentLocale]; // use any locale
if (decimalNumber != [NSDecimalNumber notANumber]) {
    // theString is number
}