标题栏消失动画（navigation）
self.mainNavigationController setNavigationBarHidden:<#(BOOL)#> animated:<#(BOOL)#>
更改标题栏颜色
self.navigationController.navigationBar.tintColor = [UIColor whiteColor];
更改电池颜色 （vc）
-(UIStatusBarStyle)preferredStatusBarStyle
{
return UIStatusBarStyleLightContent;
}
//
只需要一个静态变量就可以了
static BOOL first = YES;
if (first) {
//加载
first = NO;
}
找下层vc
id object = [self nextResponder];
while (![object isKindOfClass:[HomeViewController class]] &&
object != nil) {
object = [object nextResponder];
}
HomeViewController *homeVC = (HomeViewController *)object;
