UIScrollview Autolayout Issue

问题:

I have a problem with autolayout(maybe) and my scrollview!

My Problem

1. I scroll down

2.Then I push to another View

3.Then I go back and the scrollview looks like that and I'm not able to scroll to the highest point.(I see it in the bouncing of the scrollview)

Can anybody help me?

回答1:

The following code snippet in the containing view controller also seems to solve the problem, without relying on explicit sizes:

- (void)viewDidDisappear:(BOOL)animated {
  [super viewDidDisappear:animated];
  self.mainScrollView.contentOffset = CGPointZero;
}

It does reset the content offset to the origin, but it seems that so do the other answers.

回答2:

if you are still searching for an answer i found it today after two days of headbanging the wall. I will just paste you the code, but the most important thing is when you load your scrollView..

    -(void)viewWillAppear:(BOOL)animated{

    [scrollView setFrame:CGRectMake(0, 0, 320, 800)];
}

-(void)viewDidAppear:(BOOL)animated
{
    [scrollView setScrollEnabled:YES];
    [scrollView setContentSize:CGSizeMake(320, 800)];

}

all this is loaded before -(void)viewDidLoad

notice the height is in both instances 800, which is crucial for resolving this problem. good luck with your project ;)

回答3:

I was using adam's solution, but started to have problems when i was dismissing with animated:YES. In my code, content offset gets set a while after viewWillAppear (as viewWillAppear appears to be too soon).

- (void)viewDidDisappear:(BOOL)animated
{
    self.scrollOffsetToPersist = self.scrollView.contentOffset;
    self.scrollView.contentOffset = CGPointZero;

    [super viewDidDisappear:animated];
}

- (void)viewWillAppear:(BOOL)animated
{
    [super viewWillAppear:animated];

    [[NSOperationQueue mainQueue] addOperationWithBlock:^
     {
         self.scrollView.contentOffset = self.scrollOffsetToPersist;
     }];
}

EDIT: another, better way is to reset it back in viewDidLayoutSubviews :)

- (void)viewDidLayoutSubviews
{
    [super viewDidLayoutSubviews];

    if(!CGPointEqualToPoint(CGPointZero, self.scrollOffsetToPersist))
    {
        self.scrollView.contentOffset = self.scrollOffsetToPersist;
        self.scrollOffsetToPersist = CGPointZero;
    }
}

回答4:

This isn't great but I beat auto-layout (definitely not the correct way but I was sick of trying!) by setting the content size in viewDidAppear after autolayout happens, setting the scrollOffset and persisting the scroll offset in viewDidDisappear, and then setting the scroll offset back to it's persisted state in viewDidAppear.

Like this:

-(void)viewDidAppear:(BOOL)animated{
    [super viewDidAppear:YES];
    self.scrollView.contentSize = self.scrollViewInnerView.frame.size;
    self.scrollView.contentOffset = [self.scrollOffsetToPersist CGPointValue];

}

-(void)viewDidDisappear:(BOOL)animated{
    [super viewDidDisappear:YES];
    self.scrollOffsetToPersist = [NSValue valueWithCGPoint:self.scrollView.contentOffset];
    self.scrollView.contentOffset = CGPointZero;
}

Not at all elegant, but works so thought I'd share.

回答5:

I use an UITabBarController and different views with auto layout. The views are longer than the screen of the device. Switching from one tab to the other lead sometimes to the problem you describe. This only happened if the view has been scrolled down before the switch. I tried all the advice here but this did not work for my case. My solution was to scroll up again before leaving the view. At least a work around for this bug in iOS 6:

-(void)viewWillDisappear:(BOOL)animated {
    [super viewWillDisappear:animated];
    [scrollView setContentOffset:CGPointZero animated:NO];
}

回答6:

The issue cause ScrollView was set ContentOffset before AutoLayout applied. the solution is:

Create private property

@property (assign,nonatomic) CGPoint scrollviewContentOffsetChange;

Add code to view method

- (void)viewWillAppear:(BOOL)animated {
  [super viewWillAppear:animated];
  self.scrollView.contentOffset = CGPointZero;
}

- (void)viewWillDisappear:(BOOL)animated {
  [super viewWillDisappear:animated];
  self.scrollviewContentOffsetChange = self.scrollView.contentOffset;
}

- (void)viewDidLayoutSubviews {
  [super viewDidLayoutSubviews];

  self.scrollView.contentOffset = self.scrollviewContentOffsetChange;
}

回答7:

have you tried this?

self.automaticallyAdjustsScrollViewInsets = NO;

In my case this was what solved my problem.

回答8:

I had the same problem. Turned out I was setting a constraint on the content view aligning the it's y-center to the superview's y-center. When I deleted this constraint it worked just fine.

回答9:

try this

@property (nonatomic, assign) CGPoint scrollViewContentOffsetChange;

- (void)viewWillAppear:(BOOL)animated
{
    [super viewWillAppear:animated];
    self.scrollView.contentOffset = CGPointZero;
}

- (void)viewWillDisappear:(BOOL)animated {
    [super viewWillDisappear:animated];
    self.scrollViewContentOffsetChange = _scrollView.contentOffset;
}

- (void)viewDidLayoutSubviews {
    [super viewDidLayoutSubviews];
    _scrollView.contentOffset = self.scrollViewContentOffsetChange;
}