iPhone : How to generate random emails in Objective-C

I'm building an app that manages email contacts. I wanted to have mock data. So I wrote this code to generate random strings and emails for me:

- (NSString*) getRandomEmail

{

    NSString *answer = [NSString stringWithFormat:@"%@@%@.com", [self getRandomString], [self getRandomString]];

    return answer;

}

- (NSString*) getRandomString

{

    NSString *letters = @"abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789";

    int len = [self getRandomIntBetweenBottomInt:1 andTopInt:7];

    NSMutableString *randomString = [NSMutableString stringWithCapacity: len];

    for (int i=0; i < len; i++) {

        [randomString appendFormat: @"%C", [letters characterAtIndex: arc4random() % [letters length]]];

    }

    return randomString;

}

- (int) getRandomIntBetweenBottomInt:(int)bottom andTopInt:(int)top

{

    int randomNumber = (arc4random() % top) + bottom;

    return randomNumber;

}

and this is the result: