iOS : Creating Random E-mail and Phone Number

This is a sample code how to create random e-mail and phone number. I used it in my unit tests of authorization.

- (NSString *)randomEmail
{
    //Format:xxxxx@rdw.ru
    NSString *alphabet  = @"abcdefghijklmnopqrstuvwxyz0123456789";
    NSString *randomString = [self randomStringWithAlphabet:alphabet numberOfChars:5];
    NSString *randomEmail = [NSString stringWithFormat:@"%@@rdw.ru", randomString];
    NSLog(@"randomEmail: %@", randomEmail);
    
    return randomEmail;
}


- (NSString *)randomPhoneNumber
{
    //Format:89xxxxxxxxx
    NSString *alphabet  = @"0123456789";
    NSString *randomString = [self randomStringWithAlphabet:alphabet numberOfChars:9];
    NSString *randomPhoneNumber = [NSString stringWithFormat:@"89%@", randomString];
    NSLog(@"randomPhoneNumber: %@", randomPhoneNumber);
    
    return randomPhoneNumber;
}


- (NSString *)randomStringWithAlphabet:(NSString *)alphabet numberOfChars:(NSInteger)numberOfChars
{
    NSMutableString *s = [NSMutableString stringWithCapacity:numberOfChars];
    for (NSUInteger i = 0U; i < numberOfChars; i++) {
        u_int32_t r = arc4random() % [alphabet length];
        unichar c = [alphabet characterAtIndex:r];
        [s appendFormat:@"%C", c];
    }
    
    return s;
}