iOS的坐标真正从(0，0)开始

if ([self respondsToSelector:@selector(setEdgesForExtendedLayout:)])
{
[self setEdgesForExtendedLayout:UIRectEdgeNone];
}

在ViewDidLoad里面调用这句话。
另外如果想做导航栏穿透效果，最后是隐藏导航栏，然后自定义一个导航栏，如果在导航栏上增加遮罩的话会导致push操作卡顿现象，未解决该问题。

[self.view addSubview:self.navView];
[self.view bringSubviewToFront:self.navView];

- (void)viewWillAppear:(BOOL)animated
{
[super viewWillAppear:animated];
[[UIApplication sharedApplication] setStatusBarStyle:UIStatusBarStyleLightContent];
[self.navigationController setNavigationBarHidden:YES animated:animated];
}

- (void)viewWillDisappear:(BOOL)animated
{
[super viewWillDisappear:animated];
[self.navigationController setNavigationBarHidden:NO animated:animated];
}