NSSet和排序方法、数组去重

NSSet

去掉数组中重复的数
NSSet方法

    NSArray *arr = @[@11,@33,@44,@42,@22,@11,@44,@11];
    NSSet *set = [NSSet setWithArray:arr];
    //集合判断一个数组里面是否包含一个对象，速度最快，若重复很多次，应该考虑用集合
    //NSOrderedSet
    [set containsObject:@11];
    arr = [set allObjects];

NSDictionary方法

    NSArray *arr = @[@11,@33,@44,@42,@22,@11,@44,@11];
    NSMutableDictionary *dict = [NSMutableDictionary dictionary];
    [arr enumerateObjectsUsingBlock:^(id  _Nonnull obj, NSUInteger idx, BOOL * _Nonnull stop) {
        dict[obj] = @1;
    }];
    arr = [dict allKeys];
    
    NSLog(@"%@",arr);

数组排序

    NSArray *arr2 = @[@11,@33,@44,@42,@22,@11,@44,@11];
    NSMutableArray *arr1 = arr2.mutableCopy;
    for (int i = 0; i < arr1.count; i++) {
        for (int j = 0; j < arr1.count; j++) {
            if (arr1[i] > arr1[j]) {
                [arr1 exchangeObjectAtIndex:i withObjectAtIndex:j];
            }
        }
    }

冒泡排序

    //冒泡排序
    for (int i = 0; i < arr1.count; i++) {
        for (int j = 0; j < arr1.count - 1 - i; j++) {
            if (arr1[j] > arr1[j + 1]) {
                [arr1 exchangeObjectAtIndex:j withObjectAtIndex:j + 1];
            }
        }
    }

sort方法排序(快排)

    [arr1 sortUsingComparator:^NSComparisonResult(id  _Nonnull obj1, id  _Nonnull obj2) {
        if (obj1 > obj2) {
            //降
            return NSOrderedDescending;
        }else if(obj1 < obj2){
            //升 
            return NSOrderedAscending;
        }
        else {
            return NSOrderedSame;
        }
    }];