I have a UIImageView and two two UILabel as its child. Now using auto layouts I want that UIImageView's width should be equal to the maximum of these two labels so that both of these are visible completely. Is there a way to define this constraint?
Instead of using same width constraint (which is fine too if you specify <= constraints, but needs some extra work after) you may use leading and trailing constraints. If your imageview will have a >= leading and <= trailing constraints for both of the labels + your labels will be in their intrinsic size, then imageview will have the maximum width. This can be illustrated with the picture below:
Make sure your labels has horizontal compression resistance set to required (1000) to prevent labels from being down-resized.
You can define your constraints in the code itself and add a constraint after you know the size of the wider UILabel
Take a look at this answer on how to add constraints programmatically
https://stackoverflow.com/a/13055845
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I have an UIImageView and an UILabel next to each other with horizontal spacing constraint 0 and vertical alignment constraint. Now I want the image to be 80% as high as the label, so I set an equal height constraint with multiplier 0.8. But now instead of the image shrinking the image and the label grow insanely big. The constraint is still applied since the image is smaller than the label, but they are just way to big. My guess is that the constraint resizes the label based on the image instead of the other way around. So how can I tell it to do what I want?
Ary you trying to achieve like I shown in following image?
Where UIImageView view will be having 80% height of your UILabel?
If yes then Height Constraint will be key here.
Select both UI elements and apply Equal Heights constraint
It will make both as same height.
Then select the Height Constraint of UIImageView and add
Multiplier = 0.8 in Size inspector
Apply One by One constraints to each element first to show in expected way then add Equal Heights constraint. It will show conflict because other constraints are already present, then apply Multiplier = 0.8 and finally you are good to remove the unwanted constraints i.e. Fixed Height.
To avoid auto resizing of UIImageView according to Image, you need to have fix Height constraint for UILabel.
I am trying to achieve the following.
I have a
--> MainView
--> UIImageView 200x200
--> UILabel W:200(max) , H: Variable
--> UILabel W:Variable , H: 20
All the views in mainView are placed in sequence one after another.
Now i am trying to set autoLayout so that the mainView height is depended on its children,
E.g If i set ImageView hidden then it should wrap both UILabels etc.
How can I set autoLayout constraints so that the mainView have "Wrapping" effect over its children.
The easy way to achieve this is using a UIStackView (WWDC 2015 session video). Pure Autolayout is a lot more complicated in this case.
Assuming you would like to lay the children out vertically, left-aligned:
Controlling the Trailing Edge
Add a greater-than-or-equal 0 constraint between the trailing edge of each child and the parent's trailing edge. This will cause the widest child to push the parent's trailing edge to the right. These constraints should have a very high priority.
You will need another constraint to prevent the layout from being ambiguous. With the three trailing constraints the width of the parent is ensured not to be smaller than the widest subview. You also have to constrain the parent's width not to be greater than the widest subview's width. Just add a width constraint to the parent with a constant of 0 and a very low priority.
I like to think of that low-priority width constraint to work like a rubber band trying to pull the trailing edge as far to the left as it can. The greater-than-or-equal-to-zero constraint of the widest subview prevents it from pulling any further.
Hiding views does not have an effect since hidden views still take part in the layout calculation. You will need to keep a references to the greater-than-or-equal constraints and disable the corresponding constraint when hiding a child to take it's trailing edge out of the equation.
Controlling the Height
The heights of the children are likely defined by the view's intrinsic content size. Conceptually the Autolayout engine adds width and height constraints to the view according to the settings for content hugging and content compression resistance.
There will be two hidden height constraints for views that have an intrinsic height dimension: one for content hugging and one for content compression. Hugging constrains the height to be less than or equal to the intrinsic height. Compression resistance constrains the height to be greater than or equal to the intrinsic height. The height of the view is exactly equal to the intrinsic height if both can be fulfilled. The priorities for content compression resistance and for content hugging can be set separately for fine-grained control over when which constraint breaks.
We can use this knowledge to let the parentView's height shrink if a child is hidden. We need a "rubber band constraint" for the parent's height:
Constrain the height of the parent to zero with a low priority, say 2.
Whenever you hide a view, make sure to lower the vertical compression resistance priority of that view to a value less than the rubber band constraint priority, say 1. Now the rubber band overpowers the compression resistance constraint, causing the height of that view to collapse and the parent to shrink accordingly. Be sure to raise that priority to a value greater than the rubber band constraint when un-hiding the view to reverse the effect.
Now i am trying to set autolayouts so taht the mainView height is depended on its children
You cannot do this by constraints alone. Autolayout does not, in and of itself, normally size a view "from the inside out", i.e. by using its subview constraints. (The exception is for special self-sizing views like a scroll view's container view or a table view self-sizing cell.)
However, you can do it in code. This is what systemLayoutSizeFitting is for. You will have to perform manual layout on the superview, but you can do it easily by calling this method.
Each UI element requires 4 constraints to infer its bounds and position. The x position, y position, height and width.
Assuming you need to shrink the mainView to the height of the UILabels, set all the three constraints except the heightConstarintfor the mainView. ie, set constraints for x, y and width. Now set all the four constraints for the three child views. A constant value must be explicitly set for the heights of all the three subViews. Now the height for the mainView will be inferred from the heights of the child views. To wrap the labels, set the heightConstraint of the UIImageView to zero in code whenever required. An IBOutlet for the heightconstraint of UIImageView can be made to set it to zero.
I came across a problem when configuing the cell of UITableView. I add two labels vertically in the content view of the UITableViewCell, and I also add constraints for the top, leading and bottom layout attributes:
I think that the height of the cell can be caculated dynamically as I have set all the vertical layout and with the instrinct size of the label, the height can be inferred.
so, I can not understand the error message that IB told me.
The second problem is that the height of cell appear on the IB is not changed with the constraint I`ve make. If I decrease the bottom constraint for example, and it is the label to change its size to fit the constraint, but not the cell change its height.
If you need to add top , leading and trailing(or width) to the 1st label. Then add bottom ,leading and trailing(or width)for the bottom label. Then add bottom constraint for 1st label to 2nd label.Then by selecting both labels, add equal height constraint.It will solve your problem.
The meaning of this conflict is that when your label content is increasing dynamically, which label's content is needed to give more priority before whom.
More precisely it can be said that if you increase one of the label's content hugging priority i.e. 252 then that label's content increment and size will be given more priority for incrementing it foremost. As autolayout executes according to the priority of constraints, it faces ambiguity in terms of increasing the views of labels if you do not set the content hugging priority.
I'm trying to use autolayout constraints to automatically resize a few similarly-sized buttons in a view to give the following effect:
Before resizing
Desired effect after resizing
As you can tell, I want the buttons to be of the same size and I also want the spacing between each button to be a constant 20 points. It seems pretty simple at first, so I set the following constraints:
Buttons: space from left neighbour = 20 (inclusive of left-most and right-most buttons)
Buttons: space from right neighbour = 20 (inclusive of left-most and right-most buttons)
Buttons: same width
What actually happens after resizing
When in preview or when I test run the app in my iPhone/simulator, the button resizes and doesn't even follow the same width constraint I set for it. In fact, the view containing the views also resizes to fit the new button sizes. Anyone knows how to fix this problem purely in the interface builder?
Setting:
- equal widths of all buttons
- horizontal spacing between all buttons
- leading to superview for the first button and trailing to superview for the last button
should do the job. Unless you're having problems with the superview (e.g. ScrollView missing constraints)
In the interface builder you set the spacing constraints between buttons like you described above. Then you can command-select all of them and specify the "Equal Width" constraint to apply to the selected objects.
Finally I have oblivion how to solve this problem. I've test it works like charm.
add constraints to space items with 20 units margin
add constraint to ages
now tricky part
for each item add constraint equal widths to a parent
select all this new constraints and change its properties
set multiplier to value 1:5
set constant to -24 (6 separation between items and parent edge gives 120, this multiplied by multiplier value 1:5 gives 24)
update items frames
That's it! Picture below show how it works in interface builder:
Set simulated size to "freeform" and test different widths (I sett this to 330).
This problem is seems to be because of wrong content hugging priority and content compression Resistance priority. So you should set them as low content hugging and high compression resistance (all should have same value).
Because content hugging is the property that resist a view to grow and content compression Resistance priority is to resist a view to shrink. For more information regarding these you can found this Question.
I have a label which is going to contain a big description. I want the label to continue growing on new lines. In the image, its the label which starts with event_venue.....
The even_venue.. label has 3 constraints for now:
Vertical space with eventt_title
a horizantal space with the leading of the superview
a width constraints which defines that the label width is always less than the superview.width.
What I want to acheive is to make the event_venue.width less than superview.width, but if it has more text, it should display in new lines. Is this possible using autolayout?
This are possible steps which can create expandable UILabel
Set layouts for UILabel fixing its position
Set number of lines = 0
Set content vertical compression resistance to 1000 (this will allow text to push the label)
Since you want UILabel to expand you cannot give it fixed height constraint or its parent fixed height constraint. Sometimes depending upon condition giving height constraint is necessary to avoid error then you need to set its priority lower than vertical compression resistance
Yes, this totally is possible. I see answers here that are close to solution but not complete. Here is a solution which works with auto layout in Storyboard, no coding of sizeToFit or anything. Your modified steps would be:
Vertical space with eventt_title
A horizontal space with the leading of the superview
A horizontal space with the trailing of the superview
Set UILabel's Line Breaks as Word Wrap.
Set UILabel's lines property as 0.
I have solved a similar problem. I had to make a label that had a variable amount of text. Here's what I did:
In the storyboard, place your label with the origin where you want it.
In the Attributes Inspector, "Label" section, set the Line Breaks = Word Wrap
Fill the label with random placeholder text to the maximum shape you want. For example, if you wanted to fill the whole width and have room for a maximum of three lines of text, you could do:
abcdefghijklmnopqrstu
abcdefghijklmnopqrstu
abcdefghijklmnopqrstu
In the code, set the text of the label using setText:
[self.myLabel setText:#"MyLabelText"];
This did it for me. Your situation may be a little different in that I wasn't changing the width of the superview and it sounds like you might be. But if the width constraint is set on the label then I would expect this to work in your case, too.
I had a similar question about label resizing, and the answer that I found that was useful to me is here: UILabel Auto Size Label to Fit Text. This is a good starting source for code on how to resize your label programmatically.
I would recommend that you also add a horizontal trailing auto layout constraint from the label to the edge of the superview. Do that and you can then get rid of your current width constraint.
AutoLayout facilitate you for orientation purpose. I don think it will give you automatic expansion. You have to define label with width and height completely, otherwise you will see dots at the end of label. So you may use UITextView expanding it all over the screen. And set textView.backgroundcolot = clearColor.