Dynamic height of UITableViewCell in iOS 7 and iOS 8 not possible
I am having a hard time trying to get a table view with dynamically sized cells that should be laid out well under iOS 7 and 8. I cannot detail all the differences to be found (in "paths" from broken layouts "ways) between iOS 7 and 8. which can be created using various "tweaks", "workarounds" and whatever I've found here and elsewhere.But eventually either on iOS 7 or iOS 8 (if not both) some or all of the content the cell is displaced because the layout system breaks one of the custom "restore" constraints.
Basically I have three different types of content. And since I'm not only displaying this content in the above table view, I've wrapped the content in three subclasses UIView
. Let's call them SummaryView
s For the table view, I created three subclasses UITableViewCell
, each of which adds a corresponding one SummaryView
to it contentView
and sets it self.contentView.autoresizingMask = UIViewAutoresizingFlexibleWidth | UIViewAutoresizingFlexibleHeight
. On updateViewConstraints
I generally delete all "my" limit, which could be added before and ...
- (void)updateConstraints
{
// ...removed custom constraints before
NSDictionary *views = NSDictionaryOfVariableBindings(_summaryView);
[self addConstraints:[NSLayoutConstraint constraintsWithVisualFormat:@"H:|-[_summaryView]-|"
options:0
metrics:nil
views:views]
toView:self.contentView];
[self addConstraints:[NSLayoutConstraint constraintsWithVisualFormat:@"V:|-[_summaryView]-|"
options:0
metrics:nil
views:views]
toView:self.contentView];
[super updateConstraints];
}
As tableView:estimatedHeightForRowAtIndexPath:
I return a static estimate, depending on the type of content. In tableView:heightForRowAtIndexPath:
I am using cells "prototype" ok ...
// ..set content on prototype cell before
[prototypeCell setNeedsUpdateConstraints];
[prototypeCell layoutIfNeeded];
CGSize size = [prototypeCell systemLayoutSizeFittingSize:UILayoutFittingExpandedSize];
return size.height;
Here, usually the debugger breaks into UIViewAlertForUnsatisfiableConstraints
(on [prototypeCell layoutIfNeeded]
) s <NSLayoutConstraint:0x17409f180 'UIView-Encapsulated-Layout-Height' V:[UITableViewCellContentView:0x17019f070(44)]>
, which conflicts with other restrictions.
So I tried ...
- Setting up
tableView.rowHeight = UITableViewAutomaticDimension
as a tableviewDidLoad
- Not performed
tableView:estimatedHeightForRowAtIndexPath:
-
Through...
if (NSFoundationVersionNumber <= NSFoundationVersionNumber_iOS_7_1) { cell.contentView.frame = cell.bounds; cell.contentView.autoresizingMask = UIViewAutoresizingFlexibleLeftMargin | UIViewAutoresizingFlexibleWidth | UIViewAutoresizingFlexibleRightMargin | UIViewAutoresizingFlexibleTopMargin | UIViewAutoresizingFlexibleHeight | UIViewAutoresizingFlexibleBottomMargin; }
... before applying the contents of the cell and calculating its layout
- Execution
self.contentView.bounds = CGRectMake(0.0, 0.0, 1000, 1000);
on cell initialization - Perhaps other things that I can't remember right now as I've been in this for more than two days.
It's always the same thing, if I reach an option that doesn't complain about unsatisfactory limitations, the layout tends to get messed up. And while I see that the table view does not set a constraint by default <NSLayoutConstraint:0x17409f180 'UIView-Encapsulated-Layout-Height' V:[UITableViewCellContentView:0x17019f070(44)]>
, the constraint that is set (on the height returned tableView:heightForRowAtIndexPath:
) instead is not appropriate for the layout system.
This post is a last resort. I know that without the constraints of specific class classes, you cannot re-check them. But since I can use these views outside of the table view without issue, this shouldn't be a view constraint issue.
I think I'll come back to calculate the sizes of all view elements manually (based on [UIScreen mainScreen].bounds
) and set them directly (like widths and heights) for all subviews. So I can get the specific cell height and set the frame contentView
manually. It's a shame as he notices the layout code wonderfully ....
Regards, Gabriel
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In the end I found an acceptable solution that didn't mess up the layout code. Shortly speaking:
In the table cell, updateConstraints
I removed the constraint with _summaryView
-bottom to look down. This way, the height constraints in the content view do not interfere with the topics in the final view.
- (void)updateConstraints
{
NSDictionary *views = NSDictionaryOfVariableBindings(_summaryView);
[self addConstraints:[NSLayoutConstraint constraintsWithVisualFormat:@"H:|-[_summaryView]-|"
options:0
metrics:nil
views:views]
toView:self.contentView];
[self addConstraints:[NSLayoutConstraint constraintsWithVisualFormat:@"V:|-[_summaryView]"
options:0
metrics:nil
views:views]
toView:self.contentView];
[super updateConstraints];
}
In tableView:heightForRowAtIndexPath:
I just use intrinsicContentSize
for the cell in question to get the height:
[prototypeCell.summaryView applyStuff];
[prototypeCell layoutIfNeeded];
height = [prototypeCell intrinsicContentSize].height;
The implementation of the intrinsicContentSize
specified table cell looks like this:
- (CGSize)intrinsicContentSize
{
// Calculate the available content width if not done yet
static CGFloat availableWidth = 0.0;
if (availableWidth == 0.0) {
availableWidth = CGRectGetWidth([UIScreen mainScreen].bounds);
}
// Check if the contentView frame needs an update
if (CGRectGetWidth(self.contentView.frame) != availableWidth) {
CGRect frame = CGRectMake(0.0, 0.0, availableWidth, 100.0);
self.contentView.frame = frame;
}
[_summaryView layoutIfNeeded];
CGSize size = _summaryView.frame.size;
size.height += 2.0 * V_PADDING;
size.width += 2.0 * H_PADDING;
return size;
}
Note that for apps that support portrait and landscape mode availableWidth
, this should be reset when the orientation is changed, or shouldn't static
. * _PADDING
is the space that I want to _summaryView
have from all sides.
Next, I removed self.contentView.autoresizingMask = UIViewAutoresizingFlexibleHeight | UIViewAutoresizingFlexibleWidth
from the cell initialization code. As it has no discernible effect.
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I might be a little late in the discussion, but I had a similar problem and found a solution.
When adding constraints, add them to the contentView, not to the cell. Otherwise, "| -" and "- |" in a visual language format will create restrictions related to the cell itself, and our bad content content will not have any restrictions.
So [self addConstraints: ...];
use instead [self.contentView addConstraints: ...];
.
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