覆盖UINavigationBar以设置默认titleView [英] Overwriting UINavigationBar to set a default titleView
问题描述
我想要做的是一个带有图像的导航栏。我的主视图上有一个标签控制器，在每个标签内我都有一个UINavigationController。从我的tab / navigationController调用的UIViewController内部，我可以设置titleView没有太大问题，在viewDidLoad方法中执行此操作：
What I want to do is a navigation bar with a image on it. I have a tab controller on my main view, and inside each tab I have a UINavigationController. From inside the UIViewController that my tab/navigationController calls, I could set the titleView without much problem, doing this inside the viewDidLoad method:
self.navigationItem.titleView = [[[UIImageView alloc] initWithImage:[UIImage imageNamed:@"mylogo.png"]] autorelease];
但是，我想在此视图中替换导航栏中的所有标题，重复它似乎很难看这无处不在。所以我在委托上做了这个（在链接所有Outlet东西之后）
But, I want to replace all titles in my navigationBar for this view, and it seems ugly to repeat this everywhere. So I did this on the delegate (after linking all the Outlet stuff)
self.tabOneNavController.navigationBar.topItem.titleView = [[[UIImageView alloc] initWithImage:[UIImage imageNamed:@"mylogo.png"]] autorelease];
再次，它有效！好的，我快到了那里。
但关键是，我有5个标签，所有这些都有内置的navigationControllers。我将代码重复从每个内部视图减少到只有5次，但它仍然存在。它要求我为每个选项卡的NavController执行此操作。
Again, it worked! ok, I'm almost getting there. But the point is, I've 5 tabs and all of them have navigationControllers inside. I reduced the code repetition from every internal view to only 5 times, but it still. It requires that I do that for the NavController of each tab.
然后我尝试扩展UINavigationBar以创建我自己的，我可以在初始化程序中设置它，并且在接口构建器中将它用作对象类。但它似乎没有用。这是我做的：
Then I tried to extend the UINavigationBar to create my own, where I could set this in the initializer, and use it in the interface builder as the object class. But it doesn't seem to work. Here is what I did:
@implementation MyNavigationBar
- (id)init {
self = [super self];
self.tintColor = [UIColor greenColor];
self.topItem.title = @"testing please work";
return self;
}
@end
接口文件中的
MyNavigationBar继承来自UINavigationBar。但这没效果。我应该覆盖其他方法吗？哪一个？这是一个好习惯吗？
我甚至不确定是否应该为每个标签添加一个navigationBar，正如我所说的，我有标签，我想要一个导航栏/在其中导航。到目前为止，经过近乎死亡的经验，试图弄清楚界面构建器/出口和类是如何工作的，代码正在运行，我只是想让它成为unglify。
in the interface file MyNavigationBar inherits from UINavigationBar. But this didn't work. Should I overwrite other method? which one? is this a good practice? I'm not even sure if I should add one navigationBar for each tab, as I said, I have tabs and I want to have a navigation bar / navigate inside them. By now, after a near death experience trying to figure out how the interface builder / outlets and classes work, the code is working, I just would like to make unglify it.
谢谢！
推荐答案
重复您所描述的代码的问题有一个优雅的解决方案。 Objective-C支持称为类别的东西，它允许您向类添加方法。常见的用途是自定义导航和标签栏。在Xcode 4中，您可以执行以下操作在UINavigationBar上添加类别：
The problem of repeating code which you describe has an elegant solution. Objective-C supports something called a "category", which allows you to add methods to a class. A common use for this is to customize navigation and tab bars. In Xcode 4, you would do something like this to add a category on UINavigationBar:
按Command + N或打开新建文件对话框。接下来，从Cocoa Touch菜单中选择Objective-C category：
Hit Command+N or open the "New File" dialog. Next, choose "Objective-C category" from the Cocoa Touch menu:
单击下一步，系统将提示您输入要作为类别添加方法的类的名称。看起来应该是这样的：
Click Next and you will be prompted to enter the name of the class that you would like to add methods to as a category. It should look something like this:
然后，您应该最终得到一个保存文件对话框。这里有关于约定的快速说明。惯例是在原始类之后命名一个类别，加号，然后描述您要添加的内容。以下是您的看法：
Then, you should end up with a save file dialog. A quick note about convention here. Convention is to name a category after the original class, the plus sign, and then a description of what you're adding. Here's what yours might look like:
保存文件后，您需要得到以下内容：
Once you save your file, you will need get something like this:
看看那美丽。您现在可以覆盖默认的绘图/初始化方法以及扩展导航栏的功能。
Look at that beauty. You can now override the default drawing/init methods as well as extend the functionality of the navbar.
我建议查看 init 和 drawRect 方法，虽然我不记得人们使用哪些方法。此外，请注意，虽然在NDA下，这可能会在iOS 5中发生变化，因此请为此做好准备。
I'd suggest looking into the init and drawRect methods, although I don't remember which ones people use. Also, please note that while under NDA, this may change in iOS 5, so just be prepared for that possibility.
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