Autolayout hides Image for first start

Question

i´m using autolayout in my Custom TableViewCell which is created with a xib file, it looks like this:

Everything works like expected and is shown correct, but i get a lot of Warning Messages while scrolling down the TableView:

Unable to simultaneously satisfy constraints. Probably at least one of the constraints in the following list is one you don't want. Try this: (1) look at each constraint and try to figure out which you don't expect; (2) find the code that added the unwanted constraint or constraints and fix it. (Note: If you're seeing NSAutoresizingMaskLayoutConstraints that you don't understand, refer to the documentation for the UIView property translatesAutoresizingMaskIntoConstraints) (

"<NSLayoutConstraint:0xc3970d0 V:[UIImageView:0xc396fc0(75)]>",
"<NSLayoutConstraint:0xc3c1dc0 V:|-(10)-[UIImageView:0xc396fc0]   (Names: '|':UITableViewCellContentView:0xc396f20 )>",
"<NSLayoutConstraint:0xc3c1fc0 V:[UIImageView:0xc3b7700]-(0)-|   (Names: '|':UITableViewCellContentView:0xc396f20 )>",
"<NSLayoutConstraint:0xc3c1ff0 V:[UIImageView:0xc396fc0]-(43)-[UIImageView:0xc3b7700]>",
"<NSAutoresizingMaskLayoutConstraint:0xc3bf8c0 h=--& v=--& V:[UITableViewCellContentView:0xc396f20(126.5)]>"
)

Will attempt to recover by breaking constraint 

<NSLayoutConstraint:0xc3970d0 V:[UIImageView:0xc396fc0(75)]>

Break on objc_exception_throw to catch this in the debugger.
The methods in the UIConstraintBasedLayoutDebugging category on UIView listed in    <UIKit/UIView.h> may also be helpful.

Especially the following Part is interesting i think:

Will attempt to recover by breaking constraint 
<NSLayoutConstraint:0xc3970d0 V:[UIImageView:0xc396fc0(75)]>

So the Problem is the Height of my UIImageview on the left Top??? I tried to delete the height and many other things, but absolutely noting worked for me....what can i do? I want a fixed size for my UIImageView on the Top Left...

EDIT: Maybe the Problem could be that the bottom UIImageView is optional and sometimes its hidden, so that leads maybe to the warnings...

The important Part of my Code:

- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:    (NSIndexPath *)indexPath{

    static NSString *CellIdentifier1 = @"NewsCell";


    GTNewsCustomCell *newsCell = [tableView dequeueReusableCellWithIdentifier:CellIdentifier1];

    NSString *bottomImage = [[self.newsList objectAtIndex:indexPath.section] valueForKey:@"boardnoteImage"];

    if(bottomImage == (NSString *)[NSNull null] || bottomImage == nil || bottomImage.length == 0){

        newsCell.bottomImage.hidden = YES;
        newsCell.bottomImage.image = nil;
        newsCell.bottomConstraint.constant = 0.0f;

        [newsCell layoutIfNeeded];
    } else {

        newsCell.bottomConstraint.constant = 19.0f;
        newsCell.bottomImage.hidden = NO;
        [newsCell layoutIfNeeded];

        [newsCell.contentView addSubview:newsCell.boardNoteImage];

    }


    newsCell.titleLabel.text = [[self.newsList objectAtIndex:indexPath.section]objectForKey:@"title"];

    newsCell.messageText = [[self.newsList objectAtIndex:indexPath.section]objectForKey:@"previewMessage"];

    NSString *authorImg = [[self.newsList objectAtIndex:indexPath.section] valueForKey:@"objectImage"];


    return newsCell;
  }

EDIT 2: I made some changes and the height calculation for the cell is now:

-(CGFloat)tableView:(UITableView *)tableView heightForRowAtIndexPath:(NSIndexPath *)indexPath {

NSString *bottomImage = [[self.newsList objectAtIndex:indexPath.section] valueForKey:@"boardnoteImage"];

//Check if the bottom Image exists
if(bottomImage == (NSString *)[NSNull null] || bottomImage == nil || bottomImage.length == 0){
//        if it not exists the cell should be smaller
    return 128.0f;
}
//if the image exists the size should be 250
return 250;

}

EDIT: 3

FINALLY it works now. I have two solutions. First one is to set the Cell Height to 148.0f, to be honest i have no idea why, maybe some strange insets from my UITextView?). And the secnd solution is to delete the bottom Constraint of the bottom Image and set a fix Height for the Bottom Image!

Answer 1

Your current setup of constraints will give the bottom UIImageView a height of -1.5.

Second rule of AutoLayout - You can't have negatives!

You can see this from the error message.

From top to bottom (of the UITableViewCell) you have...

• A gap of 10.
• A height of 75.
• A gap of 43.
• A variable height (This is the big image view)
• A gap of 0.

This adds up to 128.

Now, you also have a total height of the cell from top to bottom of 126.5.

The only way to satisfy these is to set the variable height of the image view to -1.5. THIS CAN'T BE DONE It breaks the second rule of AutoLayout. And so it chooses a constraint that it thinks might help and removes it. Thus you probably get a image view height of 0 or something.

You need to change the constraints or make the cell height 128.

Answer 2

I duplicated your layout in a sample project and the only way I could reproduce your issue was by setting this in cellForRowAtIndexPath:

cell.translatesAutoresizingMaskIntoConstraints = NO;

If you're doing that, try removing it. I haven't had time to dig into the details to understand why this causes the layout to be over-constrained. But in general, I think a good rule of thumb is don't change this default value because the table view owns the layout of the cell itself. You only own the layout of the contents.