Adjusting navigationItem.titleView's frame?

Question

I noticed that the titleView\'s position depends on the rightbarbutton title. How can I set the frame of the titleView to be in the center instead?

I\'ve tried setting

Answer 1

Recently I face with the same problem, I have a complex title view whose contents may changes, so I want can show as more content as possible, my left bar button item and right bar button item has different width, so if I set it a long width, the navigation bar won't center it. As you may know when the left or right bar button item is very long, it's impossible to center the title view, so I want to center it as much as possible.

Once we set a view to self.navigationItem.titleView, the navigation bar will manage title view's frame, it's hard to center it directly, so I subclass a view which works as the real title view's container view, I set its width with the screen width, UINavigationBar with set its frame to a property value respecting to its left/right bar button item.

The container view is MDLNavigationTitleContainer and the real title view is MDLMessagesNavigationTitleView, MDLMessagesNavigationTitleView is managed by auto layout, as it's super view is MDLNavigationTitleContainer, every time its width changes, layoutSubviews will be called. The code in layoutSubviews seems a little weird, it is used to handle the push/pop animation.

@interface MDLNavigationTitleContainer ()

@property (nonatomic) CGRect oldFrame;

@end

@implementation MDLNavigationTitleContainer

- (instancetype)initWithFrame:(CGRect)frame {
    self = [super initWithFrame:frame];
    if (self) {
        UINib *nib = [UINib nibWithNibName:@"MDLMessagesNavigationTitleView" bundle:[NSBundle bundleForClass:[MDLMessagesNavigationTitleView class]]];
        self.titleView = [[nib instantiateWithOwner:nil options:nil] firstObject];
        self.titleView.translatesAutoresizingMaskIntoConstraints = NO;
        [self addSubview:self.titleView];
        NSLayoutConstraint *centerX = [NSLayoutConstraint constraintWithItem:self.titleView attribute:NSLayoutAttributeCenterX relatedBy:NSLayoutRelationEqual toItem:self attribute:NSLayoutAttributeCenterX multiplier:1 constant:0];
        NSLayoutConstraint *centerY = [NSLayoutConstraint constraintWithItem:self.titleView attribute:NSLayoutAttributeCenterY relatedBy:NSLayoutRelationEqual toItem:self attribute:NSLayoutAttributeCenterY multiplier:1 constant:0];
        NSLayoutConstraint *width = [NSLayoutConstraint constraintWithItem:self.titleView attribute:NSLayoutAttributeWidth relatedBy:NSLayoutRelationLessThanOrEqual toItem:nil attribute:NSLayoutAttributeNotAnAttribute multiplier:1 constant:0];
        width.priority = 200;
        NSLayoutConstraint *width1 = [NSLayoutConstraint constraintWithItem:self.titleView attribute:NSLayoutAttributeWidth relatedBy:NSLayoutRelationLessThanOrEqual toItem:self attribute:NSLayoutAttributeWidth multiplier:1 constant:0];
        [self addConstraint:centerX];
        [self addConstraint:centerY];
        [self addConstraint:width];
        [self addConstraint:width1];
    }
    return self;
}

- (void)layoutSubviews {
    [super layoutSubviews];

    if (!self.superview) {
        return;
    }

    if (self.center.x > [UIScreen mainScreen].bounds.size.width) {
        self.titleView.frame = self.oldFrame;
        return;
    }

    CGFloat centerX = self.center.x;

    CGFloat superWidth = [UIScreen mainScreen].bounds.size.width;
    CGFloat superCenterX = superWidth/2;
    CGFloat offsetX = superCenterX - centerX;
    CGPoint center = self.titleView.center;

    if (CGRectGetMaxX(self.titleView.frame) + offsetX < self.bounds.size.width &&
        CGRectGetMinX(self.titleView.frame) + offsetX > 0) {
        center = CGPointMake(self.bounds.size.width/2 + offsetX, self.bounds.size.height/2);
    }
    CGSize size = self.titleView.bounds.size;
    if (size.width > self.bounds.size.width) {
        size.width = self.bounds.size.width;
    }

    self.titleView.frame = CGRectMake(center.x-size.width/2, center.y-size.height/2, size.width, size.height);
    self.oldFrame = self.titleView.frame;
}

Set the title view:

MDLNavigationTitleContainer *titleView = [[MDLNavigationTitleContainer alloc] initWithFrame:CGRectMake(0, 0, [UIScreen mainScreen].bounds.size.width, 44)];
self.navigationItem.titleView = titleView;