//结合前面写的在NavigationItem.titleView添加视图，加入滑动代理，就可以在滑动TableView的时候，实现NavigationItem.titleView的变大缩小
#pragma mark - 滑动代理
- (void)scrollViewDidScroll:(UIScrollView *)scrollView
{
CGFloat offsetY = scrollView.contentOffset.y + _newsTableView.contentInset.top;//注意
/**
* 1 - offsetY/num1 = 0.45;
0.45 为最终缩小倍率
offsetY 为纵偏移量
num1=300 为要计算的值
150/165 就是滑动多少距离后，完成缩放
*/
if (offsetY < 0 && offsetY >= -150) {
_topImageView.transform = CGAffineTransformMakeScale(1 + offsetY/(-300), 1 + offsetY/(-300));
// _topImageView.layer.anchorPoint = CGPointMake(0.5, offsetY/600. + 0.5);
// NSLog(@"%lf - %lf", offsetY, 1 + offsetY/(-300));
}
else if (offsetY >= 0 && offsetY <= 165) {
_topImageView.transform = CGAffineTransformMakeScale(1 - offsetY/300, 1 - offsetY/300);
// _topImageView.layer.anchorPoint = CGPointMake(0.5, 0.5 + offsetY/600.);
}
else if (offsetY > 165) {
_topImageView.transform = CGAffineTransformMakeScale(0.45, 0.45);
// _topImageView.layer.anchorPoint = CGPointMake(0.5, 1);
}
else if (offsetY < -150) {
_topImageView.transform = CGAffineTransformMakeScale(1.5, 1.5);
// _topImageView.layer.anchorPoint = CGPointMake(0.5, 0.5);
}
CGRect frame = _topImageView.frame;
frame.origin.y = 5;
_topImageView.frame = frame;
}
