如何自定义UINavBar？

Question

我正在使用以下代码向我的应用程序添加自定义导航栏。但我希望能够根据视图更改导航栏，这可能吗？

@implementation UINavigationBar (UINavigationBarCategory)
- (void)drawRect:(CGRect)rect 
{
    UIColor *color = [UIColor colorWithRed:82/255.0 green:80/255.0 blue:81/255.0 alpha:1.0];
    UIImage *img  = [UIImage imageNamed: @"navbar.png"];
    [img drawInRect:CGRectMake(0, 0, self.frame.size.width, self.frame.size.height)];
    self.tintColor = color;
}

@end

如果没有，是否可以仅将图像而不是标题文本添加到导航栏？

Answer 1

我强烈反对使用类别来覆盖 UINavBar 上的 -drawRect，因为此设计将在即将发布的 iOS 版本上崩溃。

不过，为导航栏标题创建自定义图像和按钮非常容易。以下是我直接从我的一个应用程序的生产代码中提取的一些代码片段。它在导航栏的标题区域中创建一个自定义图像按钮，但创建图像也同样容易：

- (void) viewDidLoad {
    UIButton *titleButton = [self buttonForTitleView];
    [titleButton setTitle:newTitle forState:UIControlStateNormal];
    [titleButton sizeToFit];

    self.navigationBar.topItem.titleView = titleButton;

}

- (UIButton *) buttonForTitleView {
    if (!_buttonForTitleView) {
        UIImage *buttonImage = [UIImage imageNamed:@"button_collection_name2"];
        UIImage *pressedButtonImage = [UIImage imageNamed:@"button_collection_name2_pressed"];
        UIButton *button = [UIButton buttonWithType:UIButtonTypeCustom];
        [button setBackgroundImage: buttonImage forState : UIControlStateNormal];
        [button setBackgroundImage: pressedButtonImage forState : UIControlStateHighlighted];
        [button setFrame:CGRectMake(0, 0, buttonImage.size.width, buttonImage.size.height)];
        [button setTitleColor:[UIColor colorWithRed:38.0/255.0 green:38.0/255.0 blue:38.0/255.0 alpha:1.0] forState:UIControlStateNormal];
        [button setTitleShadowColor:[UIColor colorWithRed:230.0/255.0 green:230.0/255.0 blue:230.0/255.0 alpha:1.0] forState:UIControlStateNormal];
        button.titleLabel.adjustsFontSizeToFitWidth = YES;
        button.titleLabel.minimumFontSize = 10.0;
        button.titleEdgeInsets = UIEdgeInsetsMake(0.0, 10.0, 0.0, 10.0);
        button.titleLabel.shadowOffset = (CGSize){ 0, 1 };
        [button addTarget:self action:@selector(presentWidgetCollectionSwitchingViewController:) forControlEvents:UIControlEventTouchUpInside];
        _buttonForTitleView = [button retain];
    }    
    return _buttonForTitleView;
}

这就是按钮在应用程序 VideoBot 中的样子：

以下是使用图像作为导航栏标题的示例：

UIImage  *titleImage = [UIImage imageNamed:@"navbar_title_image"];
UIImageView *titleImageView = [[[UIImageView alloc] initWithImage:titleImage] autorelease];

UIView *container = [[[UIView alloc] initWithFrame:(CGRect){0.0, 0.0, titleImage.size.width, titleImage.size.height}] autorelease];
container.backgroundColor = [UIColor clearColor];
[container addSubview:titleImageView];

// add the view to the title
self.navigationBar.topItem.titleView= container;