1

keyBoard/Class/Shop/VC/KBShopVC.m

@@ -143,7 +143,7 @@ static const CGFloat JXheightForHeaderInSection = 50;
 
     self.naviBGView = [[UIView alloc] init];
     self.naviBGView.alpha = 0;
-    self.naviBGView.backgroundColor = [UIColor whiteColor];
+    self.naviBGView.backgroundColor = [UIColor clearColor];
     self.naviBGView.frame = CGRectMake(0, 0, KB_SCREEN_WIDTH, KB_NAV_TOTAL_HEIGHT);
     [self.view addSubview:self.naviBGView];
     UILabel *naviTitleLabel = [[UILabel alloc] init];
@@ -219,15 +219,15 @@ static const CGFloat JXheightForHeaderInSection = 50;
 
 
 - (void)pagerView:(JXPagerView *)pagerView mainTableViewDidScroll:(UIScrollView *)scrollView {
-    // 正确的吸顶阈值：头图高度 - 固定区偏移（即导航高度）
+    // 计算吸顶阈值：头图高度 - 固定区偏移（即导航高度）
     CGFloat headerH = (CGFloat)[self tableHeaderViewHeightInPagerView:self.pagerView];
     CGFloat thresholdDistance = MAX(0.0, headerH - self.pagerView.pinSectionHeaderVerticalOffset);
-    CGFloat percent = (thresholdDistance > 0 ? scrollView.contentOffset.y/thresholdDistance : 1);
-    percent = MAX(0, MIN(1, percent));
-    self.naviBGView.alpha = percent;
-    // 分类条背景：未吸顶时透明，吸顶后白色
-    // 触发吸顶的大致阈值 ≈ 头图高度 - 顶部偏移（此处用头图高度近似即可）
+
+    // 不要渐变：小于阈值 alpha=0，达到阈值(吸顶)后 alpha=1
     BOOL shouldWhite = (thresholdDistance > 0.0 && scrollView.contentOffset.y >= (thresholdDistance - 0.5));
+    self.naviBGView.alpha = shouldWhite ? 1.0 : 0.0;
+
+    // 分类条背景：未吸顶时透明，吸顶后白色
     if (shouldWhite != self.categoryIsWhite) {
         self.categoryIsWhite = shouldWhite;
         UIColor *bg = shouldWhite ? [UIColor whiteColor] : [UIColor clearColor];