//0 到 n - 1 之间的随机整数 nsuinteger r = arc4random_uniform(n); //1 到 n 之间的随机整数 nsuinteger r = arc4random_uniform(n) + 1; //0 到 1 之间的随机浮点数(double) srand48(time(0)); double r = drand48(); //nsarray 选择一个随机元素 if ([array count] > 0) { id obj = array[arc4random_uniform([array count])]; } //随机排序一个 nsarray nsmutablearray *mutablearray = [nsmutablearray arraywitharray:array]; nsuinteger count = [mutablearray count]; if (count > 1) { for (nsuinteger i = count - 1; i > 0; --i) { [mutablearray exchangeobjectatindex:i withobjectatindex:arc4random_uniform((int32_t)(i + 1))]; } } nsarray *randomarray = [nsarray arraywitharray:mutablearray]; //生成一个随机的小写 nsstring nsstring *letter = [nsstring stringwithformat:@"%c", arc4random_uniform(26) + 'a']; //从一个 nsstring 选择一个随机字符 nsstring *vowels = @"aeiouy"; nsstring *letter = [vowels substringwithrange:nsmakerange(arc4random_uniform([vowels length]), 1)];
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