Change AutoLayout Constraints during Run Time - ios

Question

How is it possible to change AutoLayout Constraints during run time.
I need to change the coordinate of view during run time so i did following:
if ([OfferText length] != 0) {
cell.topContentView.translatesAutoresizingMaskIntoConstraints = YES;
CGRect newFrame = CGRectMake( 71, 4, [Util window_width]-71,50);
cell.topContentView.frame = newFrame;
}
While doing that I get following warning. Is it possible to change the auto layout constraints during run time.
(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:0x7fca729606a0 UIView:0x7fca7296c6e0.top == UITableViewCellContentView:0x7fca729712b0.topMargin + 2>",
"<NSAutoresizingMaskLayoutConstraint:0x7fca7286f620 h=--& v=--& UIView:0x7fca7296c6e0.midY == + 29>",
"<NSAutoresizingMaskLayoutConstraint:0x7fca7286f670 h=--& v=--& V:[UIView:0x7fca7296c6e0(50)]>",
"<NSAutoresizingMaskLayoutConstraint:0x7fca705c9770 h=--& v=--& 'UIView-Encapsulated-Layout-Top' V:|-(0)-[UITableViewCellContentView:0x7fca729712b0] (Names: '|':CollectionBrandCell:0x7fca72968820 )>"
)
I find my solution using following code:
in .h of tableviewcell In my case
#property (weak, nonatomic) IBOutlet NSLayoutConstraint *constraintsTopContentView;
and in .m
if ([OfferText length] != 0) {
cell.constraintsTopContentView.constant=-4;
}

Answer 1

If you are setting up constraints from Storyboard, then make the outlet's of the constraints that are required to change the view's co-ordinates.
For Example:
If you want to change the top space of some view XYZ, then please do the following:
Select that view's top constraint and make outlet in .h file. This will
look like this.
#property (strong, nonatomic) NSLayoutConstraint *XYZ'stopConstraint;
Now, change this constraints constant, when you required by the following
code.
self.XYZ'stopConstraints.constant = youValue;
Also, please remove this line from your code as it is not necessary as per my view.
cell.topContentView.translatesAutoresizingMaskIntoConstraints = YES;

Answer 2

Create outlets for constraints you want to change (similar to UI controls); then change constant property of them.
Your warning caused because you use cell.topContentView.translatesAutoresizingMaskIntoConstraints = YES;. This will creates some new constraints (NSAutoresizingMaskLayoutConstraint) and cause conflict with olds.