CODEWITHSUNDEEP
iosuitableviewautolayoutuilabel
Siddharthan Asokan
Siddharthan Asokan

Reputation: 4441

Updating width of uilabel when subview not

I have UILabel in a UITableViewCell whose neighboring subview is UIControlSwitch. When the UIControlSwitch is hidden, the UILabel's width is expected to grow. Below is my custom class implementation: 

    - (void)setBounds:(CGRect)bounds
  {
    [super setBounds:bounds];

    self.contentView.frame = self.bounds;
  }

   - (void)layoutSubviews
  {
     [super layoutSubviews];

     [self.contentView updateConstraintsIfNeeded];
     [self.contentView layoutIfNeeded];

     self.numberLabel.preferredMaxLayoutWidth = CGRectGetWidth(self.numberLabel.frame);
     self.quoteLabel.preferredMaxLayoutWidth =    CGRectGetWidth(self.quoteLabel.frame);
 }

   @end

I have uploaded a sample code to explain the constraints on the storyboard.

The UILabel's width is not changing. If I set a trailing space between the UILabel and the UIControlSwitch, the control is partially hidden beyond the screen bounds. Hence the constraint for the UILabel has trailing space to the superview instead of the UIControlSwitch.

Upvotes: 1

Views: 324

Answers (1)

Rory McKinnel
Rory McKinnel

Reputation: 8014

When you hide a view, it still takes part in the layout process. So simply hiding your UISwitch will not cause anything to change.

So you either have to add/remove constraints, remove the UISwitch from its containing view or change how you are doing the constraints.

Option 1: Instead of hide/show do remove/add.

If you put the UISwitch in its own view, you can pin the UILabel to the switches containing view. Instead of hiding the UISwitch, remove it from its containing view. The result will be that the containing view collapses and your UILabel will stretch as long as the label is pinned to the switches view and the switches view to the edge.

Instead of show, add the UILabel back into the container view. The view will stretch and your UILabel will shrink.

Option 2: Use simple trailing constraint for UILabel.

Make your UILabel have a trailing constraint to the superview and CTRL drag that constraint into your code so you can set its value. Or you could add it manually if that is what you are doing.

Do not pin the UILabel to the UISwitch at all. Pin the UILabel to the right h§and side so it has the required position.

So your UILabel is now pinned to the right edge with an offset of your choosing. If you set this small, the UILabel will be over/under the switch. If set to the width of the switch plus left and right margin it will appear to stretch up to the switch.

In your code, you can find the width of the UISwitch by looking at its frame.

1) When the UISwitch is to be visible, set the trailing pin constraint of the UILabel to be the margin you want + width of UISwitch + margin to left of UISwitch you want.

2) When the UISwitch is to be hidden, set the trailing pin constraint of the UILabel to be the margin you want to the superview.

This should then cause the UILabel to extend to the switch when not hidden, or to the edge when the switch is hidden.

Upvotes: 1

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