How do I generate random numbers on iOS?

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旧时难觅i
旧时难觅i 2020-12-28 16:11

What is the best way to generate random numbers using Objective-C on iOS?
If I use (int)((double) rand() / ((double)(RAND_MAX) + (double) 1) * 5.0) to gener

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  • 2020-12-28 16:19

    There is a very similar question here on StackOverFlow. Here is one of the better solutions (no need for seeding):

    int r = arc4random() % 5;
    
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  • 2020-12-28 16:19

    Simple function for random number generation:

    int r = arc4random() % 42;  // generate number up to 42 (limit)
    
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  • 2020-12-28 16:20

    i use

    #define RANDOM_SEED() srandom(time(NULL))
    #define RANDOM_INT(__MIN__, __MAX__) ((__MIN__) + random() % ((__MAX__+1) - (__MIN__)))
    

    so you can give a min and max

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  • 2020-12-28 16:26

    You should seed the random number generator with the current time.

    srand(time(0));
    
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  • 2020-12-28 16:27

    Call srand() at the start of your program, it'll reseed random number generator

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  • 2020-12-28 16:43

    How random do you need? If you want random enough for crypto, then use SecRandomCopyBytes().

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