其实就是在scrollView里做控制

老板说想要一种类似支付宝的导航栏过渡切换效果,花了半天功夫把代码改好了

渐变过渡效果

做完.老板看后说不要这种效果,要那种在滚动时,向上滚动显示小图标,向下显示大图标效果!😂😂😂 心酸啊

其实是有状态栏的,由于用iphone5录得实时桌面,可能是软件问题,状态栏被挡住了,大家自行忽略!

既然时间已经花费了,就简要记录下上面两种效果的代码思路吧.
由于是公司项目,就不放完整代码了.

第二张图效果实现:

1.在viewDidLoad方法里navigationBar上添加上两种view

// 1.在viewDidLoad方法里navigationBar上添加上两种view
- (void)viewDidLoad {
    [super viewDidLoad];
    //..................其它代码
    
    [self.navigationController.navigationBar addSubview:self.navCoverView];
    [self.navigationController.navigationBar addSubview:self.functionHeaderView];
    self.functionHeaderView.hidden = NO;
}

2.设置一个属性_previousOffsetY用来记录每个上一次scrollView滚动的在Y轴的偏移量,在scrollViewWillBeginDragging:(UIScrollView *)scrollView方法里实时更新;在- (void)scrollViewDidScroll:(UIScrollView *)scrollView判断滚动趋势

#pragma mark - UIscroll代理

- (void)scrollViewDidScroll:(UIScrollView *)scrollView {
    // 1 - 计算偏移量
    CGFloat contentOffsetY = scrollView.contentOffset.y;
    CGFloat deltaY = contentOffsetY - _previousOffsetY;
//    NSLog(@"之前偏移量***%f*****现在偏移量***%f***间距**%f",
//          _previousOffsetY,scrollView.contentOffset.y,deltaY);
    if (deltaY > 0) { // 向上滚动显示大图
        self.functionHeaderView.hidden = NO;
        self.navCoverView.hidden = !self.functionHeaderView.hidden;
    } else { // 向下显示小图
        self.functionHeaderView.hidden = YES;
        self.navCoverView.hidden = !self.functionHeaderView.hidden;
    }
    self.previousOffsetY = contentOffsetY;
}

- (void)scrollViewWillBeginDragging:(UIScrollView *)scrollView {
    _previousOffsetY = scrollView.contentOffset.y;
}

- (void)scrollViewDidEndDragging:(UIScrollView *)scrollView willDecelerate:(BOOL)decelerate {
    UIView *view = nil;
    if (self.functionHeaderView.hidden == NO) {
        view = self.functionHeaderView;
    }else {
        view = self.navCoverView;
    }
    CGFloat top = view.bounds.size.height - 10;
    self.tableView.contentInset = UIEdgeInsetsMake(top, 0, 50, 0);
}

第一张图效果实现

1. 设置大图为tableHeaderView,navigationBar上添加小导航图

- (void)viewDidLoad {
    [super viewDidLoad];
    self.tableView.tableHeaderView = self.functionHeaderView;
    [self.navigationController.navigationBar addSubview:self.navCoverView];
    self.navCoverView.hidden = NO;
    self.navCoverView.alpha = 0;
}

2.在scrollViewDidScroll代理方法里设置渐变

- (void)scrollViewDidScroll:(UIScrollView *)scrollView {
    CGFloat alphaMinOffset = - 64;
    CGFloat alphaMaxOffset = self.tableView.tableHeaderView.height - 64;
    CGFloat scrollOffset = scrollView.contentOffset.y;
//    QYLog(@"****偏移了**** %zd",offset);
    // alpha 从 0 --> 1--> Max
    CGFloat alpha = (scrollOffset - alphaMinOffset) / (alphaMaxOffset - alphaMinOffset);
    UIImageView* barImageView = self.navigationController.navigationBar.subviews.firstObject;
    barImageView.alpha = 1 - alpha;
//    QYLog(@"透明度****%f",alpha);
    [self.navigationController.navigationItem.titleView setTintColor:[UIColor colorWithRed:1.0 green:1.0 blue:1.0 alpha:0]];
    self.navCoverView.alpha = alpha;
}

---

顺便记录一下,这个项目其它踩到的坑吧

---

1.设置tableview样式为UITableViewStyleGrouped

记得设置sectionFooterHeight 和 sectionHeaderHeight 的值,我此次项目由于navigatinBar的childView高度不断变化 ,设置 self.automaticallyAdjustsScrollViewInsets = NO;

/**
 *  设置表格
 */
- (void)setupTableView {
    self.tableView.allowsSelection = NO;
    self.tableView.separatorStyle = UITableViewCellSeparatorStyleNone;
    self.tableView.backgroundColor = GlobeTablviewBackgroundColor;
    self.tableView.bounces = NO;
    self.tableView.sectionFooterHeight = 5;
    // 设置内边距
    self.automaticallyAdjustsScrollViewInsets = NO;
    CGFloat top = self.functionHeaderView.bounds.size.height - 12;
     CGFloat bottom = self.functionHeaderView.bounds.size.height - 12;
    self.tableView.contentInset = UIEdgeInsetsMake(top, 0, bottom, 0);
    // 滚动条内边距
    self.tableView.scrollIndicatorInsets = UIEdgeInsetsMake(top, 0, bottom, 0);

}