Adding autolayout constraints to navigation controller programmatically

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Solution 1

In short: you can't.

The navigation controller manages the creation, configuration, and display of the navigation bar and optional navigation toolbar. It is permissible to customize the navigation bar’s appearance-related properties but you must never change its frame, bounds, or alpha values directly ... A navigation controller builds the contents of the navigation bar dynamically using the navigation item objects (instances of the UINavigationItem class) associated with the view controllers on the navigation stack

Source: Apple Docs

You would need to subclass the UINavigationBar and then instantiate the UINavigationController using initWithNavigationBarClass:toolbarClass: to do something further.

Though if you're looking for ways to customize the navbar, UIKit User Interface Guide is a good start to know what you may be able to do. But if it's going to be a text label, consider setting the bar's title property, for example.

Solution 2

Another way, after adding your custom view as a subview to UINavigationBar, manually setup position and size with an old fashion way by updating .frame property. It isn't a "flexible" solution, but simple and fast.

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Richa
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Richa

Updated on June 16, 2022

Comments

  • Richa
    Richa over 1 year

    I am trying to add constraints to a UI label I added on a navigation bar. The UI label shows a running timer

    Here is my code,

    self.label = [[UILabel alloc] initWithFrame:CGRectMake(550, 15, 150, 14)];
    self.label.text = @"Label";
    [self.label setTranslatesAutoresizingMaskIntoConstraints:NO];
    [self.navigationController.navigationBar addSubview:self.label];
    
    [self.navigationController.navigationBar addConstraint:[NSLayoutConstraint constraintWithItem:self.label
                                                           attribute:NSLayoutAttributeTrailing
                                                           relatedBy:NSLayoutRelationEqual
                                                              toItem:self.navigationController.navigationBar
                                                           attribute:NSLayoutAttributeTrailing
                                                          multiplier:1.0f
                                                            constant:-20.0f]];
    

    But I get the error 'Cannot modify constraints for UINavigationBar managed by a controller' when I run the app.

    How do I add this constraint?