Programmatically setting constraints on UITableViewCell

Question

I ve been using storyboards so far to set my constraints but I am attempting to learn how to do things programmatically. The issue at hand:

A table needs to return a cell in cellForRowAt. There I simply need to add a UILabel element that will be constraint to the top left bottom and right anchors. The table cell height is set to automatic as I don't know what the size of the label will be. My code looks as follows:

var uil = UILabel()

cell.addSubview(uil)
uil.leftAnchor.constraint(equalTo: cell.leftAnchor).isActive = true
uil.rightAnchor.constraint(equalTo: cell.rightAnchor).isActive = true
uil.topAnchor.constraint(equalTo: cell.topAnchor).isActive = true
uil.bottomAnchor.constraint(equalTo: cell.bottomAnchor).isActive = true
uil.numberOfLines = 0;
uil.text = "Some variable sized text that could be anything really";

If I don't give a frame to the UILabel I see nothing. If I do however using something like:

UILabel(frame: CGRect(x: 0 , y: 0 , width: 100, height: 100)

Then as expected I see the label but it's like the constraints don't apply.

What am I missing? Shouldn't the constraints be enough as they are fully descriptive?

Mahendra · Accepted Answer · 2017-07-26 11:13:29Z

1

If you are dynamically adding views then you need to set view.translatesAutoresizingMaskIntoConstraints = false

For more details click here

and then apply below constraints as It will work.

// align lbl from the left and right
cell.addConstraints(NSLayoutConstraint.constraintsWithVisualFormat("H:|-8-[view]-8-|", options: NSLayoutFormatOptions(rawValue: 0), metrics: nil, views: ["view": lbl]));

// align lbl from the top and bottom
cell.addConstraints(NSLayoutConstraint.constraintsWithVisualFormat("V:|-8-[view]-8-|", options: NSLayoutFormatOptions(rawValue: 0), metrics: nil, views: ["view": lbl]));

answered Jul 26, 2017 at 11:13

Mahendra

8,9624 gold badges36 silver badges59 bronze badges

Sign up to request clarification or add additional context in comments.

Comments

3stud1ant3 · Accepted Answer · 2017-07-26 11:13:19Z

1

I think you should add this line before applying constraints

uil.translatesAutoresizingMaskIntoConstraints = false

answered Jul 26, 2017 at 11:13

3stud1ant3

3,6062 gold badges14 silver badges15 bronze badges

Comments

harshal jadhav · Accepted Answer · 2017-07-26 11:37:19Z

Heres a working code snippet for you i have done it in view controller you can do the same for a cell

 var uil:UILabel!

    override func viewDidLoad() {
        super.viewDidLoad()
        self.uil = UILabel()
        self.uil?.translatesAutoresizingMaskIntoConstraints = false
        self.uil?.backgroundColor = UIColor.red
        self.uil?.text = "label text"
        self.uil.addSubview(self.uil!)
        self.uil?.leadingAnchor.constraint(equalTo: view.leadingAnchor, constant:10).isActive = true
        self.uil?.topAnchor.constraint(equalTo: view.topAnchor, constant:50).isActive = true
        self.uil?.trailingAnchor.constraint(equalTo: view.trailingAnchor, constant:-10).isActive = true
        self.uil?.heightAnchor.constraint(equalToConstant: 20.0).isActive = true


    }

shim · Accepted Answer · 2018-10-16 15:10:02Z

Here is an example of how we can apply constraints. i will take a label as an example.

UILabel *lb1;
lb1 =[[UILabel alloc]init];
self.view addSubview:lb1];

lb1.translatesAutoresizingMaskIntoConstraints = NO;

// horizontal constraint

NSLayoutConstraint *centreHorizontallyConstraint = [NSLayoutConstraint constraintWithItem:lb1 attribute:NSLayoutAttributeCenterX relatedBy:NSLayoutRelationEqual toItem:self.view attribute:NSLayoutAttributeCenterX multiplier:1 constant:0];

//vertical constraint

NSLayoutConstraint *centreVeryConstraint = [NSLayoutConstraint constraintWithItem:lb1 attribute:NSLayoutAttributeCenterY relatedBy:NSLayoutRelationEqual toItem:self.view attribute:NSLayoutAttributeCenterY multiplier:1 constant:0];

//height constraint

NSLayoutConstraint * lblheight = [NSLayoutConstraint constraintWithItem:lb1 attribute:NSLayoutAttributeHeight relatedBy:NSLayoutRelationEqual toItem:nil attribute:NSLayoutAttributeNotAnAttribute multiplier:1.0 constant:30];

//width constraint

NSLayoutConstraint * lblwidth = [NSLayoutConstraint constraintWithItem:lb1 attribute:NSLayoutAttributeWidth relatedBy:NSLayoutRelationEqual toItem:nil attribute:NSLayoutAttributeNotAnAttribute multiplier:1.0 constant:80];

//add constraint

[self.view addConstraints:@[centreHorizontallyConstraint,centreVeryConstraint,lblheight,lblwidth]];

Collectives™ on Stack Overflow

Programmatically setting constraints on UITableViewCell

4 Answers 4

Comments

Comments

Comments

Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

4 Answers 4

Comments

Comments

Comments

Comments

Your Answer

Sign up or log in

Post as a guest

Related