- (void)scrollViewDidScroll:(UIScrollView *)scrollView{

NSLog(@"offset---scroll:%f",scrollView.contentOffset.y);

UIColor *color=blue_jump_color; //blue_jump_color這個(gè)是定義的顏色宏

if (scrollView == self.tableView) { //這一步是為了保證滑動(dòng)tableview時(shí)候才讓導(dǎo)航欄變色

CGFloat offset=scrollView.contentOffset.y;? //獲取y值

????? if (offset<=0) {

? ? ? _navBackV.backgroundColor =? [color colorWithAlphaComponent:0]; // _navBackV是導(dǎo)航欄? ?

}else if(offset>0){

?????????????????? CGFloat alpha=1-((64-offset)/64);

???????????? _navBackV.backgroundColor =? [color colorWithAlphaComponent:alpha];

??????????? }

????? }

}