I have a problem with a segmented control. In iOS 8.1 it works perfect, but in iOS 7.1 I get the error pasted below and the segmented control size change automatically every time I click on the others segmented controls that interact with that one.
I deleted the segmented and created again but still happens.
I'm adding a constraint to modify the segmented control height:
NSLayoutConstraint *constraint = [NSLayoutConstraint constraintWithItem:self.segmentedControlDistances
attribute:NSLayoutAttributeHeight
relatedBy:NSLayoutRelationEqual
toItem:nil
attribute:NSLayoutAttributeNotAnAttribute
multiplier:1
constant:50];
[self.segmentedControlDistances addConstraint:constraint];
I get the following error:
"2015-04-13 12:48:58.751 KMetrix[507:607] 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:0x7bece3e0 V:[UISegmentedControl:0x7beca580(50)]>",
"<NSIBPrototypingLayoutConstraint:0x7be86180 'IB auto generated at build time for view with fixed frame' H:[UISegmentedControl:0x7beca580(123)]>"
)
Will attempt to recover by breaking constraint
<NSLayoutConstraint:0x7bece3e0 V:[UISegmentedControl:0x7beca580(50)]>
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"
I have the IBOutlet created and also the IBAction:
- (IBAction)segmentedControlDistances:(id)sender;
#property (weak, nonatomic) IBOutlet UISegmentedControl *segmentedControlUnit, *segmentedControlSports, *segmentedControlDistances;
Thanks
The NSIBPrototypingLayoutConstraint is being added by IB, most likely due to IB thinking that you have not fully described the layout in the original layout. This fits with the fact that you are adding a constraint for this in your code, which clashes with the one added automatically.
My suggestion would be to add a constraint for the height in IB. Then CTRL drag this into the .h and create an IBOutlet. Give it a default value.
This now means you have a constraint for the height which will prevent IB adding one.
Now in your code, rather than adding a constraint simply set the constant of the constraints IBOutlet to the value you want. The result will be you can set the height in code without the constraint clash.
Alternatively, the following answer seems to cover all the issues and describes how to work around the problem of auto insertion of constraints.
Trouble with AutoLayout on UITableViewCell
Related
I have a scroll view and an image view behind it and I am populating it with nibs. I am using autolayout. I have a bottom space to superview and a top space to superview on both of the views. The image view does exactly what I want it to do. For iphone 5 it is where I want it. And for the other iphones, it stays above the bottom of the screen, so it resizes correctly. The scroll view looks right on the iphone 5, but on the other phones it doesn't get resized, so it scrolls down below the view of the app. I get these messages in the log:
2012-11-21 10:42:38.576 LCHApp[12604:907] 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:0x1d8ea080 UIScrollView:0x1d8413b0.bottom == UIImageView:0x1d892110.bottom>",
"<NSAutoresizingMaskLayoutConstraint:0x1d8cca10 h=-&- v=-&- ScheduleViewNib:0x1d853630.height == UIScrollView:0x1d8413b0.height - 386>",
"<NSLayoutConstraint:0x1d8e5340 V:[UIImageView:0x1d892110]-(64)-| (Names: '|':ScheduleView:0x1d8efc30 )>",
"<NSAutoresizingMaskLayoutConstraint:0x1d8cf520 h=--& v=--& V:[ScheduleView:0x1d8efc30(480)]>",
"<NSLayoutConstraint:0x1d8eaed0 V:|-(45)-[UIScrollView:0x1d8413b0] (Names: '|':ScheduleView:0x1d8efc30 )>"
Will attempt to recover by breaking constraint
<NSLayoutConstraint:0x1d8ea080 UIScrollView:0x1d8413b0.bottom == UIImageView:0x1d892110.bottom>
I already tried
[self setTranslatesAutoresizingMaskIntoConstraints:YES];
and
[self.myScrollView setTranslatesAutoresizingMaskIntoConstraints:YES];
From what I can see this just takes off all constraints from the views. And isn't what I want.
The relationship between UIScrollView and auto layout is different from other aspects of auto layout. Basically, if simple auto layout were allowed to operate, nothing would scroll. For example, if a subview of the scroll view were pinned in the normal way by a constraint to 10 points from the top of the scroll view, it would be absolutely pinned there; it would never move, no matter how the scroll view were scrolled.
To solve this problem, a UIScrollView that uses autolayout operates in a completely new way. Therefore when you say "I am using autolayout" you must prepare for things to operate very differently from before. You must either use a single scroll view subview with translatesAutoresizingMaskIntoConstraints = YES, and an explicit content size, or else everything must have translatesAutoresizingMaskIntoConstraints = NO and the content size will be deduced implicitly based on the constraints of the subviews.
This is very well explained in https://developer.apple.com/library/content/releasenotes/General/RN-iOSSDK-6_0/index.html
Very important when using auto-layout: you must pin the right and/or bottom of the last subview to the right and/or bottom of the scroll view. This is how the scroll view knows the content size. For example:
[scrollView addConstraint:[NSLayoutConstraint constraintWithItem:lastSubView
attribute:NSLayoutAttributeRight
relatedBy:NSLayoutRelationEqual
toItem:scrollView
attribute:NSLayoutAttributeRight
multiplier:1.0
constant:0]];
My thanks to this site for providing the perfect example.
I lost hours because of this, and I hope to spare others my pain.
To get UIScrollviews to work nicely with constraints, I use this approach answered here. In that answer, I tackle how to get a vertically scrolling scrollview working that also works with device rotation. You can tweak the approach to work with horizontally scrolling scrollviews too. For scrollviews that scroll in both directions, don't add the size matching width constraint trick. But do everything else the same.
A couple of things.
make sure autolayout is on (IB on the "File Inspector Tab")
Make sure you are NOT making any changes that involve bounds, frame, etc. - this is all done by Auto constraints now
Make sure you stay away from AutoResizingMask. This will compete with your new settings.
If these are done right, you can now layout your button and it will work great. Here's how.
This error is stating that either your nib or an a control within that nib is NOT using auto layout.
I'm working with a Today Extension, displaying a UITableView. There are only a couple of items, but I get empty rows as well.
I'm able to use Auto Layout with an outlet constrain on the table view height to resize the table to fit only the rows with content.
What I'm not able to do is make the widget resize to wrap the table view. At the moment I'm left with a properly sized table and a lot of empty space.
If you want the widget's controller to be the height of the tableView, do this:
self.preferredContentSize = self.tableView.contentSize;
You should set this each time you reload your data of the tableView and the height would change. You don't have to worry about the contentSize's width because the system ignores it.
To correct your answer above, you would need to add:
self.view.translatesAutoresizingMaskIntoConstraints = NO;
That should fix the constraint warnings.
I've found a solution, it compiles and render as wanted, but triggers a warning.
Constants in Interface Builder
Simply have the table view sticking to the view controller's view edges.
Constants in the code
In viewWillAppear we can set the height of the view controller's view to be the same as the table view contentSize.
NSLayoutConstraint *heightConstraint = [NSLayoutConstraint constraintWithItem:self.view
attribute:NSLayoutAttributeHeight
relatedBy:0
toItem:nil
attribute:NSLayoutAttributeNotAnAttribute
multiplier:1
constant:self.tableView.contentSize.height];
heightConstraint.priority = UILayoutPriorityRequired;
[self.view addConstraint:heightConstraint];
[self.view needsUpdateConstraints];
[self.view setNeedsLayout];
The warning
The code above works fine, and also solves having to add the outlet constraint on the table view height, but generates this warning:
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:0x7af81290 'UIView-Encapsulated-Layout-Height' V:[UIView:0x7af7f560(171)]>",
"<NSLayoutConstraint:0x7e1c1010 V:[UIView:0x7af7f560(132)]>"
)
Will attempt to recover by breaking constraint
<NSLayoutConstraint:0x7af81290 'UIView-Encapsulated-Layout-Height' V:[UIView:0x7af7f560(171)]>
Make a symbolic breakpoint at UIViewAlertForUnsatisfiableConstraints to catch this in the debugger.
The methods in the UIConstraintBasedLayoutDebugging category on UIView listed in <UIKit/UIView.h> may also be helpful.
I want to hide UIPickerView below the screen, in this case 3.5 inch display. after learning about constraint value, finally I know what number should I put for NSLayoutAttributeTop.
here's my complete code :
NSLayoutConstraint *constraint = [NSLayoutConstraint
constraintWithItem:_pickerView
attribute:NSLayoutAttributeTop
relatedBy:NSLayoutRelationEqual
toItem:self.view
attribute:NSLayoutAttributeTop
multiplier:1.0f
constant:416.f];
[self.view addConstraint:constraint];
and when I run into my iDevice it works like I expected, except... the debugger console.. it gives me this message :
2013-09-19 12:34:01.850 Constrain2[3546:c07] 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)
(
"<NSAutoresizingMaskLayoutConstraint:0x75490d0 h=--& v=--& V:[UIView:0x715a2f0(416)]>",
"<NSLayoutConstraint:0x7159950 V:[UIPickerView:0x715a030(216)]>",
"<NSLayoutConstraint:0x71597c0 V:|-(416)-[UIPickerView:0x715a030] (Names: '|':UIView:0x715a2f0 )>",
"<NSLayoutConstraint:0x715a7a0 UIPickerView:0x715a030.bottom == UIView:0x715a2f0.bottom>"
)
when I changed the constant value into = 200.f which taken from 416 (superview) - 216 (uipickerview), debugger console is clear. no message there.
is it error message or just a warning? can it be ignored? is it possible to hide that UIPickerView below the screen without having that message appear on debugger console?
it seems that message won't appear when UIPickerView placed properly in its position. that is constant: 200.f
thank you.
No, you should not ignore that -- the system will try to fix it by removing a constraint, but I don't know if it will always remove the same one, and give you the result you want. You appear to be adding a constraint that conflicts with one you already have (I commented on that same problem in my answer to this previous question of yours). When you add a new constraint in code, you need to remove one (or more) that you made in IB that will conflict with it. However, to do what you're trying to do, you shouldn't even be adding a new constraint, you should be modifying the one you made in IB. From the error message it looks like you have a constraint from the bottom of the picker to the bottom of its superview (with 0 length). You should make an IBOutlet to that constraint (lets call it bottomCon for example), and then just modify its constant parameter in code:
self.bottomCon.constant = -216;
In any case, if you're making a constraint to a view that's near the bottom of the screen, you should make the constraints to the bottom, not the top like you do in your question. If you make the constant to the top, it won't be correct in a different screen size or orientation.
Add the line
_pickerView.translatesAutoresizingMaskIntoConstraints = NO;
before you add the constraint.
I'm having trouble with autolayout on an xcode 5 project. I am using a plain view controller inside with a navigation controller. I have a MKMapView on the top half and a UITableView on the bottom half. I am using storyboards, and have configured the prototype UITableViewCell, but I am adding the constraints through code. I have double-checked every control in the prototype and don't see any constraints configured there. My problem occurs when I add the constraints for the UITableViewCell. I have the following code in the cells:
-(void)updateConstraints {
[super updateConstraints];
//first remove old constraints
[self removeConstraints:self.constraints];
[self.nameLabel removeConstraints:self.nameLabel.constraints];
[self.addressLabel removeConstraints:self.nameLabel.constraints];
[self.rentableSquareFeetLabel removeConstraints:self.rentableSquareFeetLabel.constraints];
[self.lastSaleAmountLabel removeConstraints:self.lastSaleAmountLabel.constraints];
[self.lastSaleDateLabel removeConstraints:self.lastSaleAmountLabel.constraints];
[self.thumbnailImageView removeConstraints:self.thumbnailImageView.constraints];
//then set up constraints
NSDictionary *viewsDictionary = NSDictionaryOfVariableBindings(_thumbnailImageView, _nameLabel, _rentableSquareFeetLabel, _lastSaleAmountLabel, _addressLabel, _lastSaleDateLabel);
[self addConstraints:[NSLayoutConstraint constraintsWithVisualFormat:#"H:|[_thumbnailImageView(60)]-[_nameLabel(<=200)]-(>=8)-[_rentableSquareFeetLabel]-(>=8)-[_lastSaleAmountLabel]|" options:0 metrics:nil views:viewsDictionary]];
[self addConstraints:[NSLayoutConstraint constraintsWithVisualFormat:#"V:[_nameLabel]-(-4)-[_addressLabel]" options:NSLayoutFormatAlignAllLeading metrics:nil views:viewsDictionary]];
[self addConstraints:[NSLayoutConstraint constraintsWithVisualFormat:#"V:[_lastSaleAmountLabel]-(-4)-[_lastSaleDateLabel]" options:NSLayoutFormatAlignAllLeading metrics:nil views:viewsDictionary]];
}
I am getting the following in the debugging console. The exception is triggered by the first addConstraints line. If I just continue through those then eventually everything shows up as it should be, as it looks like xcode is choosing to break the correct constraint:
2013-09-25 15:07:14.169 PECProperties[32381:a0b] 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) (
"<NSIBPrototypingLayoutConstraint:0x9d56c70 'IB auto generated at build time for view with fixed frame' H:|-(0)-[UIImageView:0x9d558f0](LTR) (Names: '|':UITableViewCellContentView:0x9d55620 )>",
"<NSIBPrototypingLayoutConstraint:0x9d56d20 'IB auto generated at build time for view with fixed frame' H:[UIImageView:0x9d558f0(60)]>",
"<NSIBPrototypingLayoutConstraint:0x9d56d80 'IB auto generated at build time for view with fixed frame' H:|-(78)-[UILabel:0x9d559e0](LTR) (Names: '|':UITableViewCellContentView:0x9d55620 )>",
"<NSLayoutConstraint:0x9d53830 H:[UIImageView:0x9d558f0]-(NSSpace(8))-[UILabel:0x9d559e0]>" )
Will attempt to recover by breaking constraint <NSIBPrototypingLayoutConstraint:0x9d56d80 'IB auto generated at build time for view with fixed frame' H:|-(78)-[UILabel:0x9d559e0](LTR) (Names: '|':UITableViewCellContentView:0x9d55620 )>
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.
The third NSIBPrototypingLayoutConstraint shows 78 points between the edge of the view and a label. That is where the prototype is positioned roughly (and if I move it in the prototype, I see the change in the constraint in the debugging console), but that conflicts with my own constraint of "standard" distance between the image view and the label.
I have tried setting the translatesAutoresizingMaskIntoConstraints=NO in the view controller's cellForRowAtIndexPath, but that doesn't seem to be helping either. How can I fix the layout?
A few things to cover here:
The NSIBPrototypingLayoutConstraint constraints that you're running into (and that are causing exceptions) are auto-generated by Interface Builder in order to make your Storyboard or XIB view layout non-ambiguous. It's pretty sneaky about doing this, but it's automatically adding the minimum constraints required so that the position and size of each ambiguous view becomes fully specified. This is a change from Xcode 4, because in Xcode 4 you could not have ambiguous layouts in Interface Builder. With Xcode 5 and later you can, however IB will auto-generate these constraints for you if your layout is ambiguous at compile time.
The way to fix this issue is to add the minimum required constraints in Interface Builder so that each view's position & size is fully specified, then select each of these unwanted constraints, go to the right sidebar Attributes inspector, and check the box next to Placeholder - Remove at build time.
Not only does this checkbox remove the constraint you added, but most importantly it will prevent the auto-generated IB constraint from taking its place! (As you can imagine, this is quite tedious when you have a number of views in IB and want to manage all your constraints in code. For this reason you may want to avoid using IB entirely for view hierarchies in which you intend to implement Auto Layout programmatically.)
What is the difference between a Placeholder constraint and an Uninstalled constraint? Here's a slide from my Adaptive Auto Layout talk (video) (PDF slides) comparing the two:
In updateConstraints, you don't want to remove constraints and re-add them like you have there. Why not? Essentially, it's terrible for performance, and I have confirmed with Apple engineers that this is not a good idea. See the question/answer I have posted here for some more details, as well as this answer. In order to prevent constraints being added more than once, use a boolean flag (e.g. hasSetupConstraints) that you set to YES once you have set up your constraints the first time, and if updateConstraints is called again you can just return immediately if you have no new constraints to add. See this question for further discussion.
The code you're using to remove constraints may not work completely. This is because [view removeConstraints:view.constraints] will only remove constraints that have been added to view -- remember that constraints can be added to any common superview of the views they constrain -- and the constraints added to view may not be the only ones affecting the layout of view! If you need to remove a number of constraints, you should store a reference to each of those constraints in a property (e.g. an NSArray property containing NSLayoutConstraint instances), and then deactivate/remove those constraints using the API on NSLayoutConstraint or the PureLayout open-source library. You should only deactivate/remove as few constraints as possible because it is computationally expensive to do so. On the other hand, changing the constant of any constraint is very efficient and encouraged, and you don't need to remove or re-add the constraint to do that.
I'm experimenting with how to use UIScrollView. After much trouble, I finally got the hang of it. But now I've seem to hit another snag.
In this simple app, I have a scroll view with and in order for it to work, I have to set the view's bottom space to scrollview constraint to 0 as described here and it works fine. I'm doing it through the IB.
Now I've come across a scenario where I have to do that part programmatically. I've added the below code in the viewDidLoad method.
NSLayoutConstraint *bottomSpaceConstraint = [NSLayoutConstraint constraintWithItem:self.view
attribute:NSLayoutAttributeBottom
relatedBy:NSLayoutRelationEqual
toItem:self.scrollView
attribute:NSLayoutAttributeBottom
multiplier:1.0
constant:0.0];
[self.view addConstraint:bottomSpaceConstraint];
But it doesn't seem to work. It outputs the following message in the console window adn i don't know what to make of it.
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)
(
"",
""
)
Can someone please tell me how to do this? I've also attached a demo project here so that you can get a better idea on the issue.
UPDATE:
First off thanks for the responses. Using the ways mentioned in the answers I was able to get it working. However ina slightly different scenario its not. Now I'm trying to load a view onto a viewcontroller programatically.
If I may explain further. There are 2 view controllers. First one being a UITableViewController and the second one a UIViewController. Inside that a UIScrollView. Also There are multiple UIViews and some of those views' height exceeds the normal height of the screen.
The UITableViewController displays a list of options. Based on the user's selection, a particular UIView out of the lot will be loaded into the UIViewController with the UIScrollView.
In this scenario, the above method doesn't work. The scrolling isn't happening. Do I have to do something different since I'm loading the view separately?
I've uploaded a demo project here so that you can see it in action. Please see the Email.xib and select Email from the table view list.
Based upon a review of your code, a few comments:
You generally don't need to adjust constraints when a view appears. If you find yourself doing this, it often means that you haven't configured your storyboard correctly (or at least, not efficiently). The only time you really need to set/create constraints is either (a) you're adding views programmatically (which I'm suggesting is more work than it's worth); or (b) you need to do some runtime adjustment of constraints (see third bullet under point 3, below).
I don't mean to belabor it, but your project had a bunch of redundant code. E.g.
You were setting the frame for the scroll view, but that is governed by constraints, so that does nothing (i.e. when the constraints are applied, any manually set frame settings will be replaced). In general, in auto layout, don't try changing frame directly: Edit the constraints. But, no changing of constraints is needed at all anyway, so the point is moot.
You were setting the content size for the scroll view, but in auto layout, that, too, is governed by constraints (of the subviews), so that was unnecessary.
You were setting constraints for the scrollview (which were already zero), but then you weren't adding the view from the NIB into the scrollview, defeating any intent there, too. The original question was how to change the bottom constraint of the scroll view. But the bottom constraint for that is already zero, so I see no reason to set it to zero again.
I'd suggest a more radical simplification of your project:
You're making life much harder on yourself by storing your views in NIBs. It's much easier if you stay within the the storyboard world. We can help you do the NIB stuff if you really need to, but why make life so hard on yourself?
Use cell prototypes to facilitate the design of the cells in your table. You can also define the segues to go from the cells to the next scene. This eliminates any need to write any didSelectRowAtIndexPath or prepareForSegue code. Clearly, if you have something you need to pass to the next scene, by all means use prepareForSegue, but nothing you've presented thus far requires that, so I've commented it out in my examples.
Assuming you were looking for a practical example of programmatically changing constraints, I've set up the scene so that the text view will change its height programmatically, based upon the text in the text view. As always, rather than iterating through the constraints to find the one in question, when altering an existing constraint that IB created for me, I think it's far more efficient to set up an IBOutlet for the constraint, and edit the constant property for the constraint directly, so that's what I've done. So I set up the view controller to be the delegate of the text view, and wrote a textViewDidChange that updated the text view's height constraint:
#pragma mark - UITextViewDelegate
- (void)textViewDidChange:(UITextView *)textView
{
self.textViewHeightConstraint.constant = textView.contentSize.height;
[self.scrollView layoutIfNeeded];
}
Note, my text view has two height constraints, a mandatory minimum height constraint, and a medium priority constraint that I change above based upon the amount of text. The main point is that it illustrates a practical example of changing constraints programmatically. You shouldn't have to muck around with the scrollview's bottom constraint at all, but this is shows a real-world example of when you might want to adjust a constraint.
When you add a scrollview in IB, it will automatically get all the constraints you need. You probably don't want to be adding a constraint programmatically (at least not without removing the existing bottom constraint).
Two approaches might be simpler:
Create an IBOutlet for your existing bottom constraint, say scrollViewBottomConstraint. Then you can just do
self.scrollViewBottomConstraint.constant = 0.0;
Or create your view initially in IB where the bottom constraint is 0.0 and then you don't have to do anything programmatically at all. If you want to layout a long scrollview and it's subviews, select the controller, set it's simulated metrics from "inferred" to "free form". Then you can change the size of the view, set the scrollview's top and bottom constraints to be zero, layout everything you want inside the scroll view, and then when the view is presented at runtime, the view will be resized appropriately, and because you've defined the scrollview's top and bottom constraints to be 0.0, it will be resized properly. It looks a bit odd in IB, but it works like a charm when the app runs.
If you're determined to add a new constraint, you could either programmatically remove the old bottom constraint, or set the old bottom constraints' priority down as low as possible, and that way your new constraint (with higher priority) will take precedence, and the old, low-priority bottom constraint will gracefully not be applied.
But you definitely don't want to just add a new constraint.
It's possible to create outlets to represent layout constraints in your view controller. Just select the constraint you want in interface builder (e.g. via "select and edit" on the measurements pane of the view you are arranging). Then go to the outlets pane and drag a "New Referencing Outlet" to your code file (.h or .m). This will bind the constraint to an NSLayoutConstraint instance that you can access from your controller and adjust dynamically on the fly (generally via the constant property, which is poorly named because it's not a constant at all).
(Note that in XCode 6 you can double-click the constraint to select it for editing.)
Be careful when adjusting the layout in interface builder, however, as you may end up deleting the constraint and have to re-bind it to the outlet.
Looking at the console information, i feel that you are creating ambiguity when you add two same type of constraint.
So instead of creating and adding new constraint, try updating the previous constraint that is already in the constraints array.
for(NSLayoutConstraint *constraint in self.view.constraints)
{
if(constraint.firstAttribute == NSLayoutAttributeBottom && constraint.secondAttribute == NSLayoutAttributeBottom &&
constraint.firstItem == self.view && constraint.secondItem == self.scrollView)
{
constraint.constant = 0.0;
}
}
Hope this helps
Even Rob's answer will work!
You can use https://github.com/SnapKit/Masonry for adding constraints programmatically.
It is power of AutoLayout NSLayoutConstraints with a simplified, chainable and expressive syntax. Supports iOS and OSX Auto Layout.
UIView *superview = self.view;
UIView *view1 = [[UIView alloc] init];
view1.translatesAutoresizingMaskIntoConstraints = NO;
view1.backgroundColor = [UIColor greenColor];
[superview addSubview:view1];
UIEdgeInsets padding = UIEdgeInsetsMake(10, 10, 10, 10);
[superview addConstraints:#[
//view1 constraints
[NSLayoutConstraint constraintWithItem:view1
attribute:NSLayoutAttributeTop
relatedBy:NSLayoutRelationEqual
toItem:superview
attribute:NSLayoutAttributeTop
multiplier:1.0
constant:padding.top],
[NSLayoutConstraint constraintWithItem:view1
attribute:NSLayoutAttributeLeft
relatedBy:NSLayoutRelationEqual
toItem:superview
attribute:NSLayoutAttributeLeft
multiplier:1.0
constant:padding.left],
[NSLayoutConstraint constraintWithItem:view1
attribute:NSLayoutAttributeBottom
relatedBy:NSLayoutRelationEqual
toItem:superview
attribute:NSLayoutAttributeBottom
multiplier:1.0
constant:-padding.bottom],
[NSLayoutConstraint constraintWithItem:view1
attribute:NSLayoutAttributeRight
relatedBy:NSLayoutRelationEqual
toItem:superview
attribute:NSLayoutAttributeRight
multiplier:1
constant:-padding.right],]];
in just few lines
Heres the same constraints created using MASConstraintMaker
UIEdgeInsets padding = UIEdgeInsetsMake(10, 10, 10, 10);
[view1 mas_makeConstraints:^(MASConstraintMaker *make) {
make.top.equalTo(superview.mas_top).with.offset(padding.top); //with is an optional semantic filler
make.left.equalTo(superview.mas_left).with.offset(padding.left);
make.bottom.equalTo(superview.mas_bottom).with.offset(-padding.bottom);
make.right.equalTo(superview.mas_right).with.offset(-padding.right);
}];
Or even shorter
[view1 mas_makeConstraints:^(MASConstraintMaker *make) {
make.edges.equalTo(superview).with.insets(padding);
}];
do your best is sort ;)