iOS 判断字符串是否为数字

+ (BOOL)isNumber:(NSString *)strValue
{
    if (strValue == nil || [strValue length] <= 0)
    {
        return NO;
    }
    
    NSCharacterSet *cs = [[NSCharacterSet characterSetWithCharactersInString:@"0123456789."] invertedSet];
    NSString *filtered = [[strValue componentsSeparatedByCharactersInSet:cs] componentsJoinedByString:@""];
    
    if (![strValue isEqualToString:filtered])
    {
        return NO;
    }
    return YES;
}