項目中需要做滑動導航漸變的效果, 閑來無事,寫個demo 分享一下.
具體實現(xiàn)有興趣的童鞋可以下載源碼看看, 注釋寫的很清楚;

下載源碼 點這里

一蚓哩、滑動漸變

漸變

大概思路是, 隱藏導航欄, 自定義一個視圖 View, 覆蓋在原導航欄的位置, 然后在-(void)scrollViewDidScroll:(UIScrollView *)scrollView;這個方法中,根據(jù)scrollView.contentOffset.y滑動的幅度,來改變導航的背景的透明度和控件的顏色;

#pragma mark -  重點的地方在這里 滾動時候進行計算
-(void)scrollViewDidScroll:(UIScrollView *)scrollView {
    
    CGFloat offsetY = scrollView.contentOffset.y;
    
    if (offsetY <= 170) {
        self.navView.headBackImgView.alpha = offsetY/170;
        self.navView.left_bt_Img = @"tab_home";
        self.navView.right_bt_Img = @"tab_mine";
        self.navView.color = kColor(0, 0, 0, offsetY/170);
        
        [[UIApplication sharedApplication] setStatusBarStyle:UIStatusBarStyleLightContent animated:YES];
    }else{
        self.navView.headBackImgView.alpha = 1;
        
        self.navView.left_bt_Img = @"tab_home_active";
        self.navView.right_bt_Img = @"tab_mine_active";
        self.navView.color = kColor(255, 81, 81, 1);
        [[UIApplication sharedApplication] setStatusBarStyle:UIStatusBarStyleDefault animated:YES];
    }
    if (offsetY < 0) {
        CGRect rect = _backgroundImgV.frame;
        rect.size.height = _backImgHeight-offsetY;
        rect.size.width = _backImgWidth* (_backImgHeight-offsetY)/_backImgHeight;
        rect.origin.x =  -(rect.size.width-_backImgWidth)/2;
        rect.origin.y = 0;
        _backgroundImgV.frame = rect;
    }else{
        CGRect rect = _backgroundImgV.frame;
        rect.size.height = _backImgHeight;
        rect.size.width = _backImgWidth;
        rect.origin.x = 0;
        rect.origin.y = -offsetY;
        _backgroundImgV.frame = rect;
        
    }
    
    //    if (scrollView.contentOffset.y <= 0) {
    //        self.NavView.headBackView.alpha = ((240+scrollView.contentOffset.y)/140);
    //        _NavView.left_bt_Image = kMenuBTimg;
    //        _NavView.right_bt_Image = kSearchBTimg;
    //        _NavView.lab_alpha = _NavView.headBackView.alpha;
    //
    //        if (self.NavView.headBackView.alpha >= 1) {
    //
    //            _NavView.lab_alpha = 1;
    //            _NavView.headBackView.alpha = 1;
    //            _NavView.left_bt_Image = kMenuBTimg;
    //            _NavView.right_bt_Image = kSearchBTimg;
    //        }
    //    }
    
}

二仆葡、滑動隱藏導航欄 navigationBar 和 標簽欄 tabBar
同樣,在-(void)scrollViewDidScroll:(UIScrollView *)scrollView;方法中實現(xiàn)

#pragma mark UIScrollViewDelegate
- (void)scrollViewWillBeginDragging:(UIScrollView *)scrollView {
    [UIView animateWithDuration:1 animations:^{
        
        self.tabBarController.tabBar.transform = CGAffineTransformMakeTranslation(0, 49);
        
        [UIView animateWithDuration:5 animations:^{
            
            self.navigationController.navigationBar.alpha = 0;
        }];
    }];
}
- (void)scrollViewDidEndDragging:(UIScrollView *)scrollView willDecelerate:(BOOL)decelerate {
    [UIView animateWithDuration:1 animations:^{
        
        self.tabBarController.tabBar.transform = CGAffineTransformIdentity;
        self.navigationController.navigationBar.alpha = 1;
    }];
}