IOS 多标题切换,切换的标题始终在中间

Mar-05-2020 17-06-17.gif

-(void)reloadCategory{
    if (self.btnsArray.count >0) {
        [self.btnsArray enumerateObjectsUsingBlock:^(id  _Nonnull obj, NSUInteger idx, BOOL * _Nonnull stop) {
            [obj removeFromSuperview];
        }];
    }
     [self.categoryNewsArray  enumerateObjectsUsingBlock:^(NewsCategoryModel *categoryModel, NSUInteger idx, BOOL * _Nonnull stop) {
        UIButton *btn = [self categoryBtnWithTag:idx selected:self.selectIndex=idx?NO:YES title:categoryModel.categoryName];
         CGFloat w = [UILabel getWidthWithText:btn.titleLabel.text height:53 fontSize:btn.titleLabel.font];
        [btn addTarget:self action:@selector(clickAction:) forControlEvents:UIControlEventTouchUpInside];
        [self.scrollView addSubview:btn];
        [self.btnsArray addObject:btn];
        [btn mas_makeConstraints:^(MASConstraintMaker *make) {
             make.top.equalTo(self.scrollView);
             if (idx == 0) {
                 make.left.equalTo(self.scrollView).offset(10);
             }
             else
             {
                 UIButton *lastBtn = self.btnsArray[idx-1];
                 make.left.equalTo(lastBtn.mas_right);
             }
            make.width.equalTo(@(w+30));
            make.height.equalTo(@(53));
         }];
     }];
    [self.scrollView layoutIfNeeded];
    UIButton *btn = self.btnsArray.lastObject;
    self.scrollView.contentSize =CGSizeMake(btn.ly_x+btn.ly_width+10,0);
    }

-(void)clickAction:(UIButton *)sender{
    self.selectIndex = sender.tag;
    self.pageNum = 0;
    [self pullNews];
    [self.btnsArray enumerateObjectsUsingBlock:^(id  _Nonnull obj, NSUInteger idx, BOOL * _Nonnull stop) {
        [self selectStyle:idx == sender.tag?YES:NO withBtn:obj];
    }];

    //点击之后一直居中,动画保持居中
    CGPoint startPoint = [self.view convertPoint:sender.center fromView:sender.superview];
    CGFloat offset = startPoint.x - SIZE.width/2;
    CGFloat totaloffset = self.scrollView.contentOffset.x+offset;
    if(totaloffset < 0){
        totaloffset = 0;
    }
    if (totaloffset > self.scrollView.contentSize.width-SIZE.width) { //判断是否是高于最后一页
        totaloffset = self.scrollView.contentSize.width-SIZE.width;
    }
    [self.scrollView setContentOffset:CGPointMake(totaloffset, 0)];
    
}

-(UIButton *)categoryBtnWithTag:(NSInteger)tag selected:(BOOL)isSelected title:(NSString *)titleStr{
    UIButton  *btn = [[UIButton alloc] init];
    btn.tag = tag;
    [self.scrollView addSubview:btn];
    [self selectStyle:isSelected withBtn:btn];
    [btn setTitle:titleStr forState:UIControlStateNormal];
    return btn;
    
}

-(NSMutableArray *)btnsArray
{
    if (!_btnsArray) {
        _btnsArray  = [[NSMutableArray alloc] init];
    }
    return _btnsArray;
}

-(void)selectStyle:(BOOL)isSelected withBtn:(UIButton *)sender{
    if (isSelected) {
        [sender setTitleColor:Color_169FAC forState:UIControlStateNormal];
        sender.titleLabel.font = Font_b_20;
    }
    else
    {
        [sender setTitleColor:Color_777777 forState:UIControlStateNormal];
        sender.titleLabel.font = Font_b_16;
    }
}