iOS求两个数组里的相同元素

    NSArray *A = @[@1,@2,@3,@4,@5,@6,@7,@8,@9,@13];
    NSArray *B = @[@1,@2,@3,@4,@5,@6,@7,@8,@9,@10,@11,@12];

    NSMutableArray *newA = [[NSMutableArray alloc]initWithArray:A];

    NSInteger minB = [B[0] integerValue];  //取出B数组中最小的值
    for (int i=0; i<A.count; i++) {
        NSInteger minA = [A[0] integerValue];
        if (minA<minB) {
            [newA removeObjectAtIndex:i];
        }else{
            break;
        }
    }

    NSMutableArray *realA = [[NSMutableArray alloc]initWithArray:newA]; //这里注意要重新构建一个新数组，表示最终的在范围内的数组.
    NSInteger maxB = [B[B.count-1] integerValue]; //取出B数组中最大的值
    for (int i=newA.count-1; i>0; i--) {
        NSInteger maxA = [newA[i] integerValue];
        if (maxA>maxB) {
            [realA removeObjectAtIndex:i];
        }else{
            break;
        }
    }

    NSLog(@"%@",realA);


    for (int i=0; i<realA.count; i++) {
        NSNumber *valueA = realA[i];
        if ([B containsObject:valueA]) {
            NSLog(@"%@是在B数组里",valueA);
        }

    }

2019-04-16 10:09:57.922207+0800 SYAnswer[68108:3274705] (
    1,
    2,
    3,
    4,
    5,
    6,
    7,
    8,
    9
)
2019-04-16 10:09:57.922409+0800 SYAnswer[68108:3274705] 1是在B数组里
2019-04-16 10:09:57.922514+0800 SYAnswer[68108:3274705] 2是在B数组里
2019-04-16 10:09:57.922612+0800 SYAnswer[68108:3274705] 3是在B数组里
2019-04-16 10:09:57.922711+0800 SYAnswer[68108:3274705] 4是在B数组里
2019-04-16 10:09:57.922810+0800 SYAnswer[68108:3274705] 5是在B数组里
2019-04-16 10:09:57.922900+0800 SYAnswer[68108:3274705] 6是在B数组里
2019-04-16 10:09:57.922989+0800 SYAnswer[68108:3274705] 7是在B数组里
2019-04-16 10:09:57.923080+0800 SYAnswer[68108:3274705] 8是在B数组里
2019-04-16 10:09:57.923171+0800 SYAnswer[68108:3274705] 9是在B数组里

    NSArray *array1 = @[@1,@2,@3,@4,@5,@6,@7,@8,@9,@13];
    NSArray *array2 = @[@1,@2,@3,@4,@5,@6,@7,@8,@9,@10,@11,@12];
    
    NSMutableDictionary *dict = [NSMutableDictionary dictionary];
    
    for (int i=0; i<array2.count; i++) {
        [dict setObject:array2[i] forKey:array2[i]];
    }
    
    for (int i=0; i<array1.count; i++) {
        NSNumber *value = [dict objectForKey:array1[i]];
        if (value) {
            NSLog(@"数组array1中%@在数组array2中",value);
        }
    }

2019-04-16 10:20:31.367393+0800 SYAnswer[68281:3279609] 数组array1中1在数组array2中
2019-04-16 10:20:31.367543+0800 SYAnswer[68281:3279609] 数组array1中2在数组array2中
2019-04-16 10:20:31.367638+0800 SYAnswer[68281:3279609] 数组array1中3在数组array2中
2019-04-16 10:20:31.367724+0800 SYAnswer[68281:3279609] 数组array1中4在数组array2中
2019-04-16 10:20:31.367813+0800 SYAnswer[68281:3279609] 数组array1中5在数组array2中
2019-04-16 10:20:31.367905+0800 SYAnswer[68281:3279609] 数组array1中6在数组array2中
2019-04-16 10:20:31.367998+0800 SYAnswer[68281:3279609] 数组array1中7在数组array2中
2019-04-16 10:20:31.368087+0800 SYAnswer[68281:3279609] 数组array1中8在数组array2中
2019-04-16 10:20:31.368176+0800 SYAnswer[68281:3279609] 数组array1中9在数组array2中