NSString contains only decimal numbers

DecimalNumberString.m

+ (BOOL)containsOnlyDecimalNumbers1:(NSString *)string
{
    NSCharacterSet *characterSet = [NSCharacterSet characterSetWithCharactersInString:string];
    return [[NSCharacterSet decimalDigitCharacterSet] isSupersetOfSet:characterSet];
}

+ (BOOL)containsOnlyDecimalNumbers2:(NSString *)string
{
    NSCharacterSet *characterSet = [NSCharacterSet decimalDigitCharacterSet].invertedSet;
    return [string rangeOfCharacterFromSet:characterSet].length == 0;
}

+ (BOOL)containsOnlyDecimalNumbers3:(NSString *)string
{
    NSRegularExpression *regex = [NSRegularExpression regularExpressionWithPattern:@"\\d"
                                                                           options:0
                                                                             error:nil];
    NSUInteger length = string.length;
    return [regex numberOfMatchesInString:string options:0 range:NSMakeRange(0, length)] == length;
}

+ (BOOL)containsOnlyDecimalNumbers4:(NSString *)string
{
    NSRegularExpression *regex = [NSRegularExpression regularExpressionWithPattern:@"\\D"
                                                                           options:0
                                                                             error:nil];
    NSUInteger length = string.length;
    return [regex numberOfMatchesInString:string options:0 range:NSMakeRange(0, length)] == 0;
}

+ (BOOL)containsOnlyDecimalNumbers5:(NSString *)string
{
    NSPredicate *predicate = [NSPredicate predicateWithFormat:@"SELF MATCHES '\\\\d+'"];
    return [predicate evaluateWithObject:string];
}