假设在UINavigationController内设置一个UIViewControlller，而UIViewController的第一个子视图是UIScrollView的话，UIScrollview里面全部的subView都会发生下移，如图所看到的
代码为
- (void)viewDidLoad
{
[super viewDidLoad];
UIScrollView *tempScroll = [[UIScrollView alloc] initWithFrame:CGRectMake(0, 64, 320, 200)];
[tempScroll setBackgroundColor:[UIColor grayColor]];
[tempScroll setContentSize:CGSizeMake(self.view.bounds.size.width, self.view.bounds.size.height)];
[self.view addSubview:tempScroll];
UIButton *tempButton = [UIButton buttonWithType:UIButtonTypeRoundedRect];
[tempButton setBackgroundColor:[UIColor redColor]];
[tempButton setTitle:@"subView A" forState:UIControlStateNormal];
[tempButton setFrame:CGRectMake(80, 0, 80, 100)];
NSLog(@"%d",tempScroll.subviews.count);
[tempScroll addSubview:tempButton];
}
经过验证性的代码，我发现ios7有一个机制
在navigationBar，以及statusBar都显示的情况下，Navigation的当前VC，他的VC的view的子视图树的根部的第一个子视图，假设是Scrollview的话，这个scrollview的全部子视图都会被下移64个像素。
发现了这个机制之后，怎么去修正呢？
修正方案有两个
1、把scrollview的全部子视图上移64个像素。
UIView *targetView = self.view;
while (targetView.subviews.count >0 &&
![targetView isKindOfClass:[UIScrollView class]]) {
targetView = [targetView.subviews objectAtIndex:0];
}
if ([targetView isKindOfClass:[UIScrollView class]])
{
NSLog(@"you are a scrollview");
CGSize tempSize = ((UIScrollView *)targetView).contentSize;
tempSize.height -= 64;
[(UIScrollView *)targetView setContentSize:tempSize];
for (UIView *subView in targetView.subviews)
{
CGRect tempRect = subView.frame;
tempRect.origin.y -= 64;
[subView setFrame:tempRect];
}
}
2、把scrollView更改地位，是它不是子视图树的根部第一个子视图。
- (void)viewDidLoad
{
[super viewDidLoad];
UIView *tempBackGround = [[UIView alloc] initWithFrame:self.view.bounds];
[self.view addSubview:tempBackGround];
UIScrollView *tempScroll = [[UIScrollView alloc] initWithFrame:CGRectMake(0, 64, 320, 200)];
[tempScroll setBackgroundColor:[UIColor grayColor]];
[tempScroll setContentSize:CGSizeMake(self.view.bounds.size.width, self.view.bounds.size.height)];
[self.view addSubview:tempScroll];
UIButton *tempButton = [UIButton buttonWithType:UIButtonTypeRoundedRect];
[tempButton setBackgroundColor:[UIColor redColor]];
[tempButton setTitle:@"subView A" forState:UIControlStateNormal];
[tempButton setFrame:CGRectMake(80, 0, 80, 100)];
NSLog(@"%d",tempScroll.subviews.count);
[tempScroll addSubview:tempButton];
}
经过了修正如图所看到的
