I want to use auto-layout for UITableViewCells. These table cells have a dynamic height (depending on text length).
I'm using [UIView -systemLayoutSizeFittingSize:] to calculate the appropriate cell height (to return in [UITableView -heightForRowAtIndexPath:]) but I keep getting the following results:
If I pass UILayoutFittingCompressedSize, I get back a CGSize of (0,0).
If I pass UILayoutFittingExpandedSize, my app crashes with this error:
*** Assertion failure in -[NSISLinearExpression incrementConstant:], /SourceCache/Foundation_Sim/Foundation-1043.1/Layout.subproj/IncrementalSimplex/NSISLinearExpression.m:620
(My guess is that this means some number is infinite.)
My implementation is simple. I calculate the height for each object, and then cache it:
MessageCell *cell = // allocate a new cell...
// set up the cell (assign text, images, etc)
CGSize size = [cell systemLayoutSizeFittingSize:UILayoutFittingCompressedSize];
self.cellHeight = size.height; // size always equals (0, 0)
I hypothesize that this is a problem with the constraints I set, but:
If I manually set cellHeight to a large value, the cells all look fine except the height is wrong.
Interface Builder gives me no warnings about ambiguous restraints
[cell hasAmbiguousLayout] returns NO.
My cell has, among other things, an image set at 48x48, so a size of (0, 0) shouldn't satisfy all the constraints.
Any ideas?
This is what works for me (note 'contentView')
CGSize size = [cell.contentView systemLayoutSizeFittingSize:UILayoutFittingCompressedSize];
EDIT: I answered a similar question and provided a complete example, here:
How to resize superview to fit all subviews with autolayout?
It is hard to say something concrete basing on your post because you didn't post constraints that you use.
Apple Documentation:
systemLayoutSizeFittingSize:
Returns the size of the view that satisfies the constraints it holds.
Maybe you created constraints that can be interpreted in the way the size of the cell is equal to (0,0).
There is another way you can check the height of the cell with the text. You can put your text in the UITextView and then:
UITextView textView;
textView.text = #"l";
textView.font = [UIFont fontWithName:FONT_NAME size:FONT_SIZE];
//some code here
//
CGFloat cellHeight = textView.contentSize.height;
It is important to set the text and font (and every other property that can cause the change of the height of the UITextView) of the UITextView before using contentSize property. Also you must first add UITextView to the view.
////// EDIT
The problem with your approach with using constraints can be that you want to measure the cell which ISN'T added to the view so the system don't have all the informations it needs. It doesn't know how much space that will be for the space etc because it doesn't know the surrounding area of the cell
Related
I'm building a list view with self-sizing in my app using UICollectionView. Getting UICollectionViewFlowLayout to do a vertical list layout is a pain, so I'm writing my own UICollectionViewLayout subclass to do it.
My cells look a lot like regular table view cells - an image view on the left, a couple of labels vertically stacked in the center, and an accessory view on the right. The labels can wrap to a few lines and grow in font size according to the system font size setting, which is why they need to be self-sizing. Constraints are sensible - left to image view, image view to label, label to accessory, accessory to right, label to top and bottom.
To size my cells via preferredLayoutAttributesFittingAttributes, I need to get the desired height of the cell given the width of the collection view. I'd expect to use systemLayoutSizeFittingSize:horizontalPriority:verticalPriority: for this, passing a size like {desiredWidth, crazyLargeHeight}, UILayoutPriorityRequired for horizontal priority, and 1 for vertical priority. But the size I get back from systemLayoutFittingSize isn't sensible. The width is some previous width value from the cell (which doesn't necessarily match self.bounds.size.width or the passed-in layoutAttributes' size.width), and a height that works with that width. I also have tried passing a small height instead of a large one, and it still doesn't return the size it actually needs.
So how do I get the preferred height for the cell given a width value?
Sample code:
-(UICollectionViewLayoutAttributes *)preferredLayoutAttributesFittingAttributes:(UICollectionViewLayoutAttributes *)layoutAttributes
{
UICollectionViewLayoutAttributes *result = [super preferredLayoutAttributesFittingAttributes:layoutAttributes];
CGSize exampleSize = CGSizeMake(layoutAttributes.size.width, 20);
CGSize size = [self systemLayoutSizeFittingSize:exampleSize withHorizontalFittingPriority:UILayoutPriorityRequired verticalFittingPriority:1];
result.size = size;
return result;
}
Turns out if you ask the cell's content view for a size instead of the cell itself, it works. And you have to give a sample height that is smaller than will be needed.
-(UICollectionViewLayoutAttributes *)preferredLayoutAttributesFittingAttributes:(UICollectionViewLayoutAttributes *)layoutAttributes
{
UICollectionViewLayoutAttributes *result = [super preferredLayoutAttributesFittingAttributes:layoutAttributes];
CGSize exampleSize = CGSizeMake(layoutAttributes.size.width, 20); //magic number for example purposes...my cell will definitely be taller
CGSize size = [self.contentView systemLayoutSizeFittingSize:exampleSize withHorizontalFittingPriority:UILayoutPriorityRequired verticalFittingPriority:1];
result.size = size;
return result;
}
I'm guessing that the content view isn't pinned to the cell's bounds the way I expected. And this exact implementation will likely fall down if the content view is inset for some reason. But the key to solving this was the fact that having the cell contents pinned to the cell's content view does not mean that the cell itself will compute a size as you expect.
The Goal
I'm trying to create a dynamic message cell using auto-layout.
What I've Tried
The cell is positioning correctly, for the most part, with auto-layout given the following constraints:
The Problem
My first problem was the message label (Copyable Label) width was constrained. That seems to be resolved by using setPreferredMaxLayoutWidth: as described in this question.
Height is still a problem. As you can see, the message bubble is still cutting off. In addition, I'm not sure how to determine the message cell height for the table view.
I expected auto-layout to somehow just work. I've read the answer here, but it seems like a lot to of steps.
The Question
First, is a case where auto-layout is more complex than traditional frame arithmetic?
Second, using auto-layout, how can I determine the height of the resulting cell?
I fully use Auto Layout and what you speak about is kinda a problem.
I didn't want to modify the way intrinsic size is calculated for performance purpose of UITable.
So I used a very simple way that is correct in the end. It's ok if your cell is simple, can become such hard if your cell contains more than one variable text.
I defined my cells normally, where you can put a UILabel that fits the insets (no problem about it).
Then, in your table datasource, you define directly the height of the cell:
- (CGFloat)tableView:(UITableView *)tableView heightForRowAtIndexPath:(NSIndexPath *)indexPath {
return [TEXTOFYOURCELL sizeWithFont:[UIFont systemFontOfSize:14] constrainedToSize:CGSizeMake(300, 1000)].height + 31; // Here it's defined for 15 of top and bottom insets, define +1 than the size of the cell is important.
}
EDIT :
Here some code about the UILabel in the cell (in init method).
__titleLabel = [UILabel new];
__titleLabel.numberOfLines = 0;
[self.contentView addSubview:__titleLabel]; // adding to contentView rather than self is very important !
[__titleLabel keepInsets:UIEdgeInsetsMake(0, 15, 0, 15)];
I use this API : https://github.com/iMartinKiss/KeepLayout to manage auto layout simpler.
This is possible on iOS 8 as can be read on AppCoda
Basically:
Set the label lines to 0.
Set the row height UITableViewAutomaticDimension
I made a custom cell, placed a UITextView inside it and I want to change the height of the cell based on the length of UITextView's text length. I know how to statically change the cell height using heightForRowAtIndexPath, but I can't put my head around doing it dynamically, based on content.
I have read about a dozen topics on this forum and on several other, but I didn't find the answer I was looking for.
Any ideas?
in heightForRowAtIndexPath
float height = [cell.textView.text sizeWithFont:cell.textView.font constrainedToSize:CGSizeMake(cell.textView.frame.size.width, 10000)].height;
return height;
10000 it's max height of cell, actually you can set max integer value
In your textViewDidChange method, call
[tableView beginUpdates];
[tableView endUpdates];
This will trigger heightForRowAtIndexPath to recalculate all your cell sizes each time the user types a letter. Then in heightForRowAtIndexPath, you can then calculate the necessary size for your cell.
The sizeWithFont method will return the size needed to display the text in a UILabel, which is slightly different than that for a UITextView due to content insets, line spacing, etc. I've used a somewhat hacky solution in the past. If you create a temporary UITextView, set it's text, and use [UIView sizeThatFits:constraintSize] to get the size that will fit all its content within the constraints. (The documentation on this method is a little unclear - take a look at this answer for more info: question about UIView's sizeThatFits)
UITextView *temp = [UITextView alloc] initWithFrame:someArbitraryFrame];
temp.font = DISPLAY_FONT
temp.text = cell.textView.text;
//This gets the necessary size to fit the view's content within the specified constraints
CGSize correctSize = [self.temp sizeThatFits:CGSizeMake(CONSTRAINT_WIDTH, CONSTRAINT_HEIGHT)];
return correctSize.height
In interest of efficiency, you should probably store/lazy-load the temporary textView so that you're not creating a new UITextView for every cell, but rather re-using the same one to calculate height for different text.
I have a uilabel setup in a view. It doesn't have a width constraint, but its width is instead determined by a leading constraint to the thumbnail image, and a trailing constraint to the edge of the view.
The label is set to have 0 lines, and to word wrap. My understanding is that this should cause the frame of the uilabel to grow, and indeed it does sometimes. (Previous to auto layout, I would calculate and update the frame of the label in code).
So the result is, it works correctly in some instance and not others. See most cells working correctly there, but the last cell appears to be too big. In fact it's the right size. The title "Fair Oaks Smog Check Test" actually ends with "Only". So my calcuation for the cell size is right, it should be that size. However the label doesn't wrap the text for whatever reason. It's frame width does not extend off to the right, so that's not the issue.
So what is going on here? It's 100% consistent, always on that cell and not the ones above it, which makes me think it's related to the size of the text, and UILabel isn't re-laying out the text once this view is added to the cell (which makes it actually smaller width wise).
Any thoughts?
Some additional information
The height of the cells is calculated from one sample cell I create and store in a static variable:
- (CGFloat) tableView:(UITableView *)tableView heightForRowAtIndexPath:(NSIndexPath *)indexPath {
if (self.items.count == 0) {
return 60;
}
static TCAnswerBuilderCell *cell = nil;
static dispatch_once_t pred;
dispatch_once(&pred,
^{
// get a sample cellonce
cell = [tableView dequeueReusableCellWithIdentifier:TC_ANSWER_BUILDER_CELL];
});
[cell configureCellWithThirdPartyObject:self.items[indexPath.row]];
return [cell heightForCellWithTableWidth:self.tableView.frame.size.width];
}
I configure the cell with my data object on the fly, and then call a method I have on it which calculates the height of the cell with a given table width (can't always rely on the cell frame being correct initially).
This in turn calls a height method on my view, since it is really where the label lives:
- (CGFloat)heightForCellWithTableWidth:(CGFloat)tableWidth {
// subtract 38 from the constraint above
return [self.thirdPartyAnswerView heightForViewWithViewWidth:tableWidth - 38];
}
This method determines the height by figuring out the correct width of the label, and then doing a calculation:
- (CGFloat)heightForViewWithViewWidth:(CGFloat)viewWidth {
CGFloat widthForCalc = viewWidth - self.imageFrameLeadingSpaceConstraint.constant - self.thumbnailFrameWidthConstraint.constant - self.titleLabelLeadingSpaceConstraint.constant;
CGSize size = [self.titleLabel.text sizeWithFont:self.titleLabel.font constrainedToSize:CGSizeMake(widthForCalc, CGFLOAT_MAX) lineBreakMode:NSLineBreakByWordWrapping];
CGFloat returnHeight = self.frame.size.height - self.titleLabel.frame.size.height + size.height;
CGFloat height = returnHeight < self.frame.size.height ? self.frame.size.height : returnHeight;
return height;
}
This works 100% correctly.
The cells are created obviously in cellForRowAtIndexPath and immediately configured:
if (self.items.count > 0) {
TCAnswerBuilderCell *cell = [tableView dequeueReusableCellWithIdentifier:TC_ANSWER_BUILDER_CELL forIndexPath:indexPath];
[cell configureCellWithThirdPartyObject:self.items[indexPath.row]];
return cell;
}
In configuration of the cell, my view is loaded from a nib (it's re-used elsewhere, which is why it's not directly in the cell). The cell adds it as follows:
- (void) configureCellWithThirdPartyObject:(TCThirdPartyObject *)object {
self.detailDisclosureImageView.hidden = NO;
if (!self.thirdPartyAnswerView) {
self.thirdPartyAnswerView = [TCThirdPartyAPIHelper thirdPartyAnswerViewForThirdPartyAPIServiceType:object.thirdPartyAPIType];
self.thirdPartyAnswerView.translatesAutoresizingMaskIntoConstraints = NO;
[self.contentView addSubview:self.thirdPartyAnswerView];
[self.contentView addConstraints:[NSLayoutConstraint constraintsWithVisualFormat:#"|[_thirdPartyAnswerView]-38-|" options:NSLayoutFormatAlignAllCenterY metrics:nil views:NSDictionaryOfVariableBindings(_thirdPartyAnswerView)]];
}
[self.thirdPartyAnswerView configureViewForThirdPartyObject:object forViewStyle:TCThirdPartyAnswerViewStyleSearchCell];
}
Finally my view configuration looks like this:
- (void) configureViewForThirdPartyObject:(TCTPOPlace *)object forViewStyle:(TCThirdPartyAnswerViewStyle) style {
self.titleLabel.text = object.name;
self.addressLabel.text = [NSString stringWithFormat:#"%#, %#, %#", object.address, object.city, object.state];
self.ratingsLabel.text = [NSString stringWithFormat:#"%d Ratings", object.reviewCount];
NSString *ratingImageName = [NSString stringWithFormat:#"yelp_star_rating_%.1f.png", object.rating];
UIImage *ratingsImage = [UIImage imageNamed:ratingImageName];
if (ratingsImage) {
self.ratingImageView.image = ratingsImage;
}
if (object.imageUrl) {
[self.thumbnailImageView setImageWithURL:[NSURL URLWithString:object.imageUrl] completed:nil];
}
}
A sort of solution, but I don't understand why
My subview was designed at 320 width, but has no constraints of its own for width
The subview was added to the cell, but with horizontal constraints that look like this:
#"|[_thirdPartyAnswerView]-38-|"
The view was configured immediately after being added to the cell, meaning the text for the titleLabel was set right then.
For whatever reason, the text was laid out as if the view had the full 320 instead of 282.
The label was never updated, even though the frame of the subview was updated to 282, and there were constraints on the label that would keep it sized correctly.
Changing the size of the view in the xib to be 282 fixed the issue, because the label has the right size to begin with.
I'm still not understanding why the label doesn't re-lay out after the size of the parent view is updated when it has both leading and trailing constraints.
SOLVED
See Matt's answer below: https://stackoverflow.com/a/15514707/287403
In case you don't read the comment, the primary problem was that I was unknowingly setting preferredMaxLayoutWidth via IB when designing a view at a bigger width than it would be shown (in some cases). preferredMaxLayoutWidth is what is used to determine where the text wraps. So even though my view and titleLabel correctly resized, the preferredMaxLayoutWidth was still at the old value, and causing wrapping at unexpected points. Setting the titleLabel instead to it's automatic size (⌘= in IB), and updating the preferredMaxLayoutWidth dynamically in layoutSubviews before calling super was the key. Thanks Matt!
I'm someone who has written an app that uses autolayout of five labels in a cell in a table whose cells have different heights, where the labels resize themselves according to what's in them, and it does work. I'm going to suggest, therefore, that the reason you're having trouble might be that your constraints are under-determining the layout - that is, that you've got ambiguous layout for the elements of the cell. I can't test that hypothesis because I can't see your constraints. But you can easily check (I think) by using po [[UIWindow keyWindow] _autolayoutTrace] when paused in the debugger.
Also I have one other suggestion (sorry to just throw stuff at you): make sure you're setting the label's preferredMaxLayoutWidth. This is crucial because it's the width at which the label will stop growing horizontally and start growing vertically.
I had the same problem and solved it using a suggestion from this answer. In a subclass of UILabel I placed this code:
- (void)layoutSubviews
{
[super layoutSubviews];
self.preferredMaxLayoutWidth = self.bounds.size.width;
}
I don't understand why this is not the default behavior of UILabel, or at least why you cannot just enable this behavior via a flag.
I am a little concerned that preferredMaxLayoutWidth is being set in the middle of the layout process, but I see no easy way around that.
Also, check that you are passing integral numbers to your layout constraints in code.
For me it happened that after some calculations (e.g. convertPoint:toView:), I was passing in something like 23.99999997, and eventually this lead to a 2-line label displaying as a one-liner (although its frame seemed to be calculated correctly). In my case CGRectIntegral did the trick!
Rounding errors could kill ya :)
I know this is a very common issue here on stack overflow, however, i haven't been able to figure out what is going on by looking at the various threads on the topic.
I've got a nib file with a UITableViewCell subclass and a UILabel in the cell. The desired behavior is for the UILabel to expand vertically and display multiple lines of text (if the text is long enough). I've set the number of lines property in interface builder to 0, and I've also set the line breaks to word wrap (also in interface builder). When I display the cell, I am setting the height of the cell to be a function of sizeWithFont: constrainedToSize: linebreakmode: using the text of the cell. The height is returning correctly for the cell, however the UILabel does not wrap, nor does it expand vertically.
Any idea what might be going wrong?
Thanks!
**UPDATE
Here is the code I used to calculate the height of the cell:
+ (CGFloat)heightForCellGiveText:(NSString *)text
{
CGSize size = [text sizeWithFont:[self defaultMainFont] constrainedToSize:CGSizeMake(LABEL_WIDTH, CGFLOAT_MAX) lineBreakMode:NSLineBreakByWordWrapping];
return size.height + (2 * VERT_PADDING) + INTER_LABEL_PADDING;
}
I was hoping to let interface builder automatically handle everything having to do with actually resizing the label (and not the cell)