Can I center a UIToolbar item?

问题

I am putting a label on a UIToolbar (per this tip: Adding a UILabel to a UIToolbar).

But the toolbar has a button on the left side, and so flexible spaces throw the label off the center, which is where I'd like it to be. Can I somehow center this toolbar item so that it remains centered in the toolbar?

(Already tried balancing the button with a dummy fixed space, no dice.)

Thanks!

回答1:

Simplest way would be to put the label above the bar, in it's parent view, and justify it there.

回答2:

Add a flexible space item to the left and right of your center item, like you did. Then add a fixed space item at the end and set the width to whatever the left button width is -- somewhere around 28 pixels.

UIBarButtonItem *fixedItem = [[[UIBarButtonItem alloc] initWithBarButtonSystemItem:UIBarButtonSystemItemFixedSpace target:nil action:NULL] autorelease];
fixedItem.width = 28;

回答3:

To center a text/title on a toolbar you can use a simple UILabel like see below:

UILabel *labelTitle = [[UILabel alloc] init];
labelTitle.font =[UIFont fontWithName:@"Helvetica-Bold" size:18];
labelTitle.backgroundColor = [UIColor clearColor];
labelTitle.textAlignment = UITextAlignmentCenter;
labelTitle.userInteractionEnabled = NO;
labelTitle.text = @"Your Title";
[labelTitle sizeToFit];
CGRect labelTitleFrame = labelTitle.frame;
labelTitleFrame.size.width = self.toolbar.bounds.size.width;
labelTitleFrame.origin.y = (self.toolbar.bounds.size.height - labelTitleFrame.size.height) / 2;
labelTitle.frame = labelTitleFrame;
labelTitle.autoresizingMask = UIViewAutoresizingFlexibleWidth;
// Just add UILabel like UIToolBar's subview 
[self.toolbar addSubview:labelTitle];
[labelTitle release];
labelTitle = nil;

回答4:

Yes we can center a toolbar item just put two flexible space in the toolbar like :

UIBarButtonItem *flexibaleSpaceBarButton = [[UIBarButtonItem alloc] initWithBarButtonSystemItem:UIBarButtonSystemItemFlexibleSpace target:nil action:nil];

toolbar.items = [NSArray arrayWithObjects:loginButton,flexibaleSpaceBarButton,toolBarLabel,flexibaleSpaceBarButton, nil];

来源：https://stackoverflow.com/questions/2511135/can-i-center-a-uitoolbar-item