objective-c 将类作为参数传递？
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Pass a class as a parameter?
提问by JoBu1324
I have been lead to believe that it is possible to pass a class as a method parameter, but I'm having trouble implementing the concept. Right now I have something like:
我一直认为可以将类作为方法参数传递，但是我在实现这个概念时遇到了麻烦。现在我有类似的东西：
- (id)navControllerFromView:(Class *)viewControllerClass
title:(NSString *)title
imageName:(NSString *)imageName
{
viewControllerClass *viewController = [[viewControllerClass alloc] init];
UINavigationController *thisNavController =
[[UINavigationController alloc] initWithRootViewController: viewController];
thisNavController.tabBarItem = [[UITabBarItem alloc]
initWithTitle: title
image: [UIImage imageNamed: imageName]
tag: 3];
return thisNavController;
}
and I call it like this:
我这样称呼它：
rootNavController = [ self navControllerFromView:RootViewController
title:@"Contact"
imageName:@"my_info.png"
];
What's wrong with this picture?
这张图有什么问题？
回答by Peter Hosey
- (id)navControllerFromView:(Class)viewControllerClass
- (id)navControllerFromView:(Class)viewControllerClass
It's just Class, without the asterisk. (Classisn't a class name; you're not passing a pointer to an instance of the Classclass, you're passing the class itself.)
它只是Class，没有星号。（Class不是类名；您不是传递指向Class类实例的指针，而是传递类本身。）
rootNavController = [ self navControllerFromView:RootViewController
rootNavController = [ self navControllerFromView:RootViewController
You can't pass a bare class name around like this—you have to send it a message. If you actually want to pass the class somewhere, you need to send it the classmessage. Thus:
你不能像这样传递一个空的类名——你必须给它发送一条消息。如果你真的想在某个地方传递类，你需要向它发送class消息。因此：
rootNavController = [self navControllerFromView:[RootViewController class]
title:@"Contact"
imageName:@"my_info.png"
];
回答by Ben Gotow
It looks like you've almost got it. You want to pass [RootViewController class]instead of RootViewController. That gives you a Classvalue. Also, I don't think you want your function to take a Class *, just a Class. It's not actually an Objective-C object.
看起来你已经差不多了。你想通过[RootViewController class]而不是RootViewController. 这给了你一个Class价值。另外，我认为您不希望您的函数采用Class *，而只是采用Class. 它实际上不是一个 Objective-C 对象。
回答by Steven Canfield
You haven't explained any problem with the code you've posted. What doesn't work? What are you expecting to happen? The only thing I can think of so far is that you might want to pass [RootViewController class]instead of just RootViewController. Also, your formatting is killing me.
您还没有解释您发布的代码有任何问题。什么不起作用？你期待发生什么？到目前为止，我唯一能想到的是您可能想要通过[RootViewController class]而不是RootViewController. 此外，您的格式正在杀死我。
回答by Adam Johns
In Swift:
在斯威夫特：
func acceptingFunction(aClass: AnyClass) {
...
}
call with:
致电：
acceptingFunction(UIView)
