UIScrollView不会在iOS 7中滚动到底部

Question

In this following code example self.contentView refers to the UIScrollView in question.

// Scroll to bottom.
CGPoint bottomOffset = CGPointMake(0, self.contentView.contentSize.height - 
                                   self.contentView.bounds.size.height);
if (bottomOffset.y >= 0.0)
{
    [self.contentView setContentOffset:bottomOffset animated:YES];
}

Oddly, in iOS 6 this works perfectly fine, but in iOS 7 the scroll view (assuming it has a contentSize that's vertically larger than it's frame.size.height ) only scrolls to the very bottom of the bottom most subview added to the scroll view.

For example, if the following cases hold true:

self.contentView.frame.size.height == 50.0
self.contentView.contentSize.height == 100.0

aSubView.frame.origin.y == 50.0
aSubView.frame.size.height == 20.0

The scrolling code will only scroll until aSubView is visible; self.contentView.contentOffset.y == 20.0 rather than self.contentView.contentOffset.y == 50.0 which would be at the bottom of the entire scroll view.

This is (of course) occurs until programmatically another subview is added to self.contentView (via a user interaction), then everything corrects itself.

For clarity, I set breakpoints before and after the scrolling code to measure changes to self.contentView.contentOffset .

Other fun fact, if I remove animated and set the contentOffset directly it works as expected on iOS 7, but I'd prefer keeping the animation.

NOTE: Not using interface builder

Answer 1

仅一行..您可以滚动到底部..！

[yourScrollview scrollRectToVisible:CGRectMake(yourScrollview.contentSize.width - 1, yourScrollview.contentSize.height - 1, 1, 1) animated:YES];

Answer 2

So I figured out a pretty unsatisfying solution rather quickly by wrapping the call in an async dispatch block.

// Scroll to bottom.
CGPoint bottomOffset = CGPointMake(0, self.contentView.contentSize.height
                                   - self.contentView.bounds.size.height);
if (bottomOffset.y >= 0.0)
{
    dispatch_async(dispatch_get_main_queue(), ^{
        [self.contentView setContentOffset:bottomOffset animated:YES];
    });
}

If anyone understands what is really causing the problem and can provide a better solution I'd gladly accept that as the answer, but for everyone else dealing with the same issue hopefully this works for you as well.

Answer 3

Disabling "Adjust Scroll View Insets" solved this for me. (Xcode 6, iOS 8)

Answer 4

You can deselecting 'Use Autolayout' in the File Inspector pane of main view within the Scroll View.This may help u. UIScrollView doesn't scroll after upgrading to iOS7 / xcode 5