iOS 7 Custom UINavigationBar TitleView moves when

问题:

I am using a custom title view for a UINavigationBar with the following code:

// Set a label to the nav bar
THLabel *titleLabel = [[THLabel alloc] init];
titleLabel.text = @"Test";
titleLabel.font = [UIFont fontWithName:APP_FONT size:22.0];
titleLabel.frame = CGRectMake(0, 0, 100, 30);
titleLabel.textAlignment = NSTextAlignmentCenter;
titleLabel.textColor = CUSTOM_LIGHT_BLUE;
titleLabel.strokeColor = kStrokeColor;
titleLabel.strokeSize = kStrokeSize;
self.navigationItem.titleView = titleLabel;

The problem is that when presenting a new viewcontroller and then returning to the original view controller this custom view shifts and then re-centers itself. Please see the video for a demonstration of that.

Please see the video here: https://www.youtube.com/watch?v=961CCVQmpJM&feature=youtu.be

I have disabled autoresizing of every subview for the navigation controller with both the storyboard and in code for each view controller:

    // Set the navigation bar hidded on the log in view
    UINavigationController* mainViewController = (UINavigationController*)self.appDelegate.window.rootViewController;
    [mainViewController setNavigationBarHidden:YES];
    [[mainViewController navigationBar] setAutoresizesSubviews:NO];

However it still resizes! How can I stop this - what am I doing wrong? Thanks!

回答1:

It's reproducible for me only if I place setting titleView code in viewWillAppear. Moving it to viewDidLoad fixes the issue

回答2:

I would embed the label inside a UIView. Interface Builder doesn't like putting directly a UILabel in the titleView for some reason that may be related to your problem.

Also try to set the autoResizingMask to UIViewAutoresizingFlexibleTopMargin. In my experience any custom view in bars behaves better this way.

回答3:

Expanding on @Alex Peda's answer above, I'm finding that on iOS7, outside of viewDidLoad, there appears to be a minimum title width for a custom title. Here's what I'm doing, below. Note there are a few methods below particular to my code.

#define MAX_TITLE_WIDTH 400
#define MIN_TITLE_WIDTH 150

- (void) setNavBarTitle: (NSString *) newTitle;
{
    if (!newTitle) newTitle = @"";
    NSMutableString *title = [newTitle mutableCopy];

    if (![_titleView.text isEqualToString:title]) {

        NSAttributedString *attrTitle = [UIAppearance attributedString:title withFontType:FontTypeTitle | FontTypeBold | FontTypeItalic size: 40.0 andOtherAttributes:@{NSForegroundColorAttributeName: [UIColor blackColor]}];
        _titleView.attributedText = attrTitle;
        [_titleView sizeToFit];

        // In iOS7, if you set the nav bar title with a custom view outside of viewDidLoad, there appears to be a minimum title width. Narrower custom view titles are not centered properly. I'm working around this by centering the text in the label, and setting the width of the label to the minimum width.
        if ([Utilities ios7OrLater]) {
            if (_titleView.frameWidth < MIN_TITLE_WIDTH) {
                _titleView.textAlignment = NSTextAlignmentCenter;
                _titleView.frameWidth = MIN_TITLE_WIDTH;
            }
        }

        if (_titleView.frameWidth > MAX_TITLE_WIDTH) {
            _titleView.frameWidth = MAX_TITLE_WIDTH;
        }
    }

    self.navigationItem.titleView = _titleView;
}

回答4:

This happened for me as well. Two things you could do :

1) make sure navigation setup is done in either viewDidLayoutSubviews or viewDidLoad as mentioned in the above answer

2) i had left and right bar button item as nil, but only called them after the title label was set. make sure to set the right and left bar button items as nil (if you are not using them of course) before setting the titlelabel to titleview.

回答5:

In my case it happened because I was setting UIBarButton before titleView. Setting titleView should be first. Works perfectly now.

回答6:

What worked for me was to create a variable in the view controller that holds your desired title view then initialize it in viewDidLoad. Then you can set that view to the self.navigationItem.titleView in viewWillAppear and it should display properly. No need for setting autoResizeMask, or rightBarButtons, etc.

Example:

class ViewController {
    var myTitleImage: UIImageView!

    override func viewDidLoad() {
        super.viewDidLoad()
        myTitleImage = UIImageView(frame: CGRect(x: 0, y: 0, width: 25, height: 25))
        myTitleImage.contentMode = .scaleAspectFit
        myTitleImage.image = #imageLiteral(resourceName: "my_title_image")
        // etc...
    }

    override func viewWillAppear(_ animated: Bool) {
        super.viewWillAppear(animated)
        self.navigationItem.titleView = self.myTitleImage
    }    
}