iOS-关于随机数总结

C语言随机函数rand() random() drand48()
OC随机函数arc4random() arc4random_uniform()

rand()

// 生成m~n之间的随机整数
-(int)randFrom:(int)m to:(int)n{
    static BOOL isSranded = NO;
    if (!isSranded) {
        isSranded = YES;
        srand((int)time(0));
    }
    return m + rand()%(n - m + 1);
}

random()

// 生成m~n之间的随机整数
-(int)randomFrom:(int)m to:(int)n{
    static BOOL isSranded = NO;
    if (!isSranded) {
        isSranded = YES;
        srandom((int)time(0));
    }
    return m + random()%(n - m + 1);
}

drand48()

// 生成0~1之间的随机浮点数
-(double)drand0To1{
    static BOOL isSranded = NO;
    if (!isSranded) {
        isSranded = YES;
        srand48(time(0));
    }
    return drand48();
}

arc4random()

// 生成m~n之间的随机整数
-(int)arc4randomFrom:(int)m to:(int)n{
    return m + arc4random()%(n - m + 1);
}

rac4random_uniform(int upper_bound)

// 生成0~N之间的随机整数
-(NSInteger)randomN:(int)n{
    return arc4random_uniform(n+1);
}

// 生成1~N之间的随机整数
-(NSInteger)random1ToN:(int)n{
    return arc4random_uniform(n) + 1;
}

实例应用

// 获取数组中随机的一个元素
-(id)randomArrayObject:(NSArray *)array{
    if ([array isKindOfClass:[NSArray class]] && [array count] > 0) {
        return array[arc4random_uniform((int)array.count)];
    }
    return nil;
}

// 获取1~100之间的不重复的长度是10的随机整数数组
-(NSArray *)getRandomArray  
{  
    NSMutableArray *seedsArray=[NSMutableArray array];
    for (int i = 0 ; i < 100; i++) {
        [seedsArray addObject:@(i+1)];
    }
    NSMutableArray *resultArray=[NSMutableArray array];  
    
    NSInteger n = 10;  
    for (int i = 0; i < n; i++) {  
        int m = arc4random_uniform((int)seedsArray.count);  
        [resultArray addObject:seedsArray[m]];  
        [seedsArray removeObjectAtIndex:m];  
    }  
    return resultArray;  
}

// 随机排序数组
-(NSArray *)randomSortArray:(NSArray *)array{
    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))];
        }
    }
    return [NSArray arrayWithArray:mutableArray];
}