在 UINavigationBar 中居中 UILabel答案

【问题标题】：centering UILabel in UINavigationBar在 UINavigationBar 中居中 UILabel
【发布时间】：2012-04-19 06:03:14
【问题描述】：

我有一个 UINavigationBar 并设置了 leftBarButtonItem 和 rightBarButtonItem。左边栏设置为：

UIButton *backButton = [UIButton buttonWithType:UIButtonTypeCustom];
        [backButton setImage:[UIImage imageNamed:@"back.png"] forState:UIControlStateNormal];
        UIBarButtonItem *myButton = [[[UIBarButtonItem alloc] initWithCustomView:backButton] autorelease];
        self.navigationItem.leftBarButtonItem = myButton;

而rightbarbutton设置为：

UIButton *doneBtn = [UIButton buttonWithType:UIButtonTypeCustom];
 UIImage *doneButtonImage = nil;
        doneButtonImage = [UIImage imageNamed:@"done.png"];
        [doneBtn setImage:doneButtonImage forState:UIControlStateNormal];
  doneBarButtonItem = [[UIBarButtonItem alloc] initWithCustomView:doneBtn];
    self.navigationItem.rightBarButtonItem = doneBarButtonItem;

back 的宽度是 23px，done 是 72px，所以它们不相等。现在的问题是我有一个标签，我想一直在中心。如果标签中的文本太长而干扰右栏按钮，我想剪辑文本。我是这样设置的：

titleLabel = [[UILabel alloc] initWithFrame:CGRectZero];
    titleLabel.text = self.pageTitle; // Can't change
    titleLabel.adjustsFontSizeToFitWidth = YES;
    titleLabel.clipsToBounds = YES;
    titleLabel.numberOfLines = 1;
    titleLabel.font = [UIFont fontWithName:@"PTSans-Narrow" size:30.0]; 
    titleLabel.textColor = [UIColor colorWithWhite:0.6 alpha:1.0];
    titleLabel.backgroundColor = [UIColor yellowColor];
    titleLabel.autoresizingMask = UIViewAutoresizingFlexibleHeight;
    titleLabel.textAlignment = UITextAlignmentCenter;
    [titleLabel sizeToFit];
    titleLabel.frameHeight = self.navigationController.navigationBar.frameHeight;


 self.navigationItem.titleView = titleLabel;

但是这不会使标题居中。我该怎么做？

【问题讨论】：

只需手动将框架中的 x 值设置为使其看起来居中的任何值。
或者使用工具栏并在所有内容之间添加灵活的空格项

标签： iphone objective-c ios ipad uinavigationbar

【解决方案1】：

我建议先计算 self.pageTitle 的宽度然后相应地设置titleLabel的位置。我更喜欢这个：-

titleLabel = [[UILabel alloc] init];
titleLabel.text = self.pageTitle; // Can't change

**CGSize maximumTitleLabelSize = CGSizeMake(200,40);//Set maximum width that an self.pageTitle can have.
CGSize expectedLabelSize = [titleLabel.text titleLabel.font 
                                            constrainedToSize:maximumTitleLabelSize
                                                lineBreakMode:UILineBreakModeWordWrap];
//adjust the label the the new width.
CGRect newFrame = titleLabel.frame;
newFrame.size.width = expectedLabelSize.width;
titleLabel.size.width = newFrame.size.width;**    
if(titleLabel.size.width==100)
{
titleLabel.frame = cgRectMake(85,5,titleLabel.size.width,30);
}
else if(titleLabel.size.width==200)
{
titleLabel.frame = cgRectMake(36,5,titleLabel.size.width,30);
}

titleLabel.adjustsFontSizeToFitWidth = YES;
titleLabel.clipsToBounds = YES;
titleLabel.numberOfLines = 1;
titleLabel.font = [UIFont fontWithName:@"PTSans-Narrow" size:30.0]; 
titleLabel.textColor = [UIColor colorWithWhite:0.6 alpha:1.0];
titleLabel.backgroundColor = [UIColor yellowColor];
titleLabel.autoresizingMask = UIViewAutoresizingFlexibleHeight;
titleLabel.textAlignment = UITextAlignmentCenter;
[titleLabel sizeToFit];
titleLabel.frameHeight = self.navigationController.navigationBar.frameHeight;

self.navigationItem.titleView = titleLabel;

试试这个。它会帮助你。谢谢:)

【讨论】：

【解决方案2】：

这是最简单的解决方案，在添加到titleView之前使用sizeToFit方法：

UILabel *titleLabel = [[UILabel alloc] init];
titleLabel.text = @"My Title";
titleLabel.font = [UIFont boldSystemFontOfSize:17.0f];
titleLabel.textColor = [UIColor whiteColor];
[titleLabel sizeToFit];

self.navigationItem.titleView = titleLabel;

【讨论】：

【解决方案3】：

不要使用 NavigationItem 添加左右栏按钮，而是使用 addsubview 方法为导航栏添加自定义按钮。

【讨论】：

【解决方案4】：

使用工具栏为您的导航栏添加多个按钮。

   // create a toolbar to have two buttons in the right
UIToolbar* tools = [[UIToolbar alloc] initWithFrame:CGRectMake(0, 0, 133, 44.01)];

// create the array to hold the buttons, which then gets added to the toolbar
NSMutableArray* buttons = [[NSMutableArray alloc] initWithCapacity:3];

// create a standard "add" button
UIBarButtonItem* bi = [[UIBarButtonItem alloc]`enter code here`
initWithBarButtonSystemItem:UIBarButtonSystemItemAdd target:self action:NULL];
bi.style = UIBarButtonItemStyleBordered;
[buttons addObject:bi];
[bi release];

// create a spacer
bi = [[UIBarButtonItem alloc]
initWithBarButtonSystemItem:UIBarButtonSystemItemFixedSpace target:nil action:nil];
[buttons addObject:bi];
[bi release];

// create a standard "refresh" button
bi = [[UIBarButtonItem alloc]
initWithBarButtonSystemItem:UIBarButtonSystemItemRefresh target:self action:@selector(refresh:)];
bi.style = UIBarButtonItemStyleBordered;
[buttons addObject:bi];
[bi release];

// stick the buttons in the toolbar
[tools setItems:buttons animated:NO];

[buttons release];

// and put the toolbar in the nav bar
self.navigationItem.rightBarButtonItem = [[UIBarButtonItem alloc] initWithCustomView:tools];
[tools release];

【讨论】：

【解决方案5】：

您只需使用此代码，它的工作正常尝试一下

UILabel *titleLabel = [[UILabel alloc]initWithFrame:CGRectMake(0, 5, 190, 30)];
titleLabel.textColor = [UIColor whiteColor];
titleLabel.textAlignment = UITextAlignmentCenter;
titleLabel.text =@"My Wish List"; 
titleLabel.backgroundColor = [UIColor clearColor];
titleLabel.font = [UIFont fontWithName:@"Copperplate" size:16.0];
titleLabel.minimumFontSize = 10;
titleLabel.autoresizingMask=UIViewAutoresizingFlexibleWidth;
self.navigationItem.titleView = titleLabel;
[titleLabel release];

我也在我的项目中使用这个代码...... :-)

【讨论】：