一个Item自排的算法

static const NSInteger SortTitleItemColumn = 5;
static const NSInteger SortTitleRowHeight = 48.0;

- (UIView *)sortView {
    if (!_sortView) {
        UIView *sortView = [[UIView alloc] init];
        sortView.backgroundColor = UPContentBGColor;
        _sortView = sortView;
    
        CGFloat itemSpace = 11.4;
        CGFloat leftMargin = 15;
        CGFloat itemWidth = (UPScreenWidth - leftMargin * 2 - itemSpace * 4) / SortTitleItemColumn;
        NSMutableArray *buttonArray = [NSMutableArray arrayWithCapacity:3];
        for (int i = 0; i < self.sortTitleArray.count; i ++) {
            UPButton *button = [UPButton buttonWithStyle:UPButtonStyleClickAlpha];
            button.backgroundColor = UPRColorInModule(@"up_market_optional_news_tag_background_color", @"UPMarket");
            [button setTitleColor:UPMajorTextColor forState:UIControlStateNormal];
            [button setTitleColor:UPSelectEnableColor forState:UIControlStateSelected];
            button.titleLabel.font = UPFont(13);
            button.layer.cornerRadius = 12.5;
            button.layer.masksToBounds = YES;
            button.tag = i;
            [button setTitle:self.sortTitleArray[i] forState:UIControlStateNormal];
            if (i == 0) {
                button.selected = YES;
            }
            [button addTarget:self action:@selector(onTypeButton:) forControlEvents:UIControlEventTouchUpInside];
            [sortView addSubview:button];
            
            int currentRow = floor(i / SortTitleItemColumn);
            [button mas_makeConstraints:^(UPMASConstraintMaker *make) {
                make.height.equalTo(@25);
                make.width.equalTo(@(itemWidth));
                make.top.equalTo(sortView).offset(15 + currentRow * SortTitleRowHeight);
                int j = i;
                if (i % SortTitleItemColumn == 0) j = 0;
                make.left.equalTo(sortView).offset((itemWidth + itemSpace) * j + leftMargin);
            }];
            
            [buttonArray addObject:button];
        }
        _typeButtonArray = [buttonArray copy];
    }
    return _sortView;
}

- (CGFloat)sortViewHeight {
    CGFloat itemSpace = 11.4;
    CGFloat leftMargin = 15;
    CGFloat itemWidth = (UPScreenWidth - leftMargin * 2 - itemSpace * 4) / SortTitleItemColumn;
    CGFloat oneRowH = SortTitleRowHeight;
    CGFloat itemsW = itemWidth * self.sortTitleArray.count + itemSpace * (self.sortTitleArray.count - 1) + leftMargin * 2;
    NSInteger row = (NSInteger)ceilf(itemsW / UPScreenWidth);
    CGFloat sumH = oneRowH * row;
    return sumH;
}

- (NSArray *)sortTitleArray {
    if (!_sortTitleArray) {
        if (self.listType == UPNewsListTypeOptionalNews) {
            _sortTitleArray = nil;
        } else if (self.listType == UPNewsListTypeOptionalNotice) {
            _sortTitleArray = @[@"全部", @"利好", @"利空"];
        } else {
            _sortTitleArray = @[@"全部", @"买入", @"增持", @"减持", @"卖出"];
        }
    }
    return _sortTitleArray;
}