随机生成4个字符的字符串代码,Objectc代码库,德仔网

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【Objectc】随机生成4个字符的字符串

作者:松茂 / 发布于2016/6/12/ 542

- (NSString *)shuffledAlphabet {
    NSString *alphabet = @"abcdefghijklmnopqrstuvwxyz";
     
    // Get the characters into a C array for efficient shuffling
    NSUInteger numberOfCharacters = [alphabet length];
    unichar *characters = calloc(numberOfCharacters, sizeof(unichar));
    [alphabet getCharacters:characters range:NSMakeRange(0, numberOfCharacters)];
     
    // Perform a Fisher-Yates shuffle
    for (NSUInteger i = 0; i < numberOfCharacters; ++i) {
        NSUInteger j = (arc4random_uniform(numberOfCharacters - i) + i);
        unichar c = characters[i];
        characters[i] = characters[j];
        characters[j] = c;
    }
     
    // Turn the result back into a string
    NSString *result = [NSString stringWithCharacters:characters length:numberOfCharacters];
    free(characters);
     
    NSString *theFourString = [result substringToIndex:4];
     
     
    return theFourString;
}

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　随机生成　　随机　　生成　　字符串　

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