ios Objective-C 传递方法作为参数
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Objective-C passing methods as parameters
提问by Hymansonkr
How do you pass one method as a parameter to another method? I'm doing this across classes.
如何将一个方法作为参数传递给另一个方法？我正在跨班级这样做。
Class A:
A类：
+ (void)theBigFunction:(?)func{
// run the func here
}
Class B:
B类：
- (void)littleBFunction {
NSLog(@"classB little function");
}
// somewhere else in the class
[ClassA theBigFunction:littleBFunction]
Class C:
C类：
- (void)littleCFunction {
NSLog(@"classC little function");
}
// somewhere else in the class
[ClassA theBigFunction:littleCFunction]
回答by Filip Radelic
The type you are looking for is selector (SEL) and you get a method's selector like this:
您正在寻找的类型是选择器 ( SEL) 并且您会得到一个方法的选择器，如下所示：
SEL littleSelector = @selector(littleMethod);
If the method takes parameters, you just put :where they go, like this:
如果该方法接受参数，您只需将:它们放在何处，如下所示：
SEL littleSelector = @selector(littleMethodWithSomething:andSomethingElse:);
Also, methods are not really functions, they are used to send messages to specific class (when starting with +) or specific instance of it (when starting with -). Functions are C-type that doesn't really have a "target" like methods do.
此外，方法并不是真正的函数，它们用于向特定类（以 + 开头时）或它的特定实例（以 - 开头时）发送消息。函数是 C 类型的，它不像方法那样真正具有“目标”。
Once you get a selector, you call that method on your target (be it class or instance) like this:
一旦你得到一个选择器，你就可以像这样在目标（无论是类还是实例）上调用该方法：
[target performSelector:someSelector];
A good example of this is UIControl's addTarget:action:forControlEvents:method you usually use when creating UIButtonor some other control objects programmatically.
这方面的一个很好的例子是UIControl的addTarget：动作：forControlEvents：在创建时通常使用的方法UIButton或一些其他的控制对象编程。
回答by bryanmac
Another option is to look at blocks. It allows you to pass a block of code (a closure) around.
另一种选择是查看块。它允许你传递一个代码块（一个闭包）。
Here's a good write up on blocks:
这是一个关于块的好文章：
http://pragmaticstudio.com/blog/2010/7/28/ios4-blocks-1
http://pragmaticstudio.com/blog/2010/7/28/ios4-blocks-1
Here's the apple docs:
这是苹果文档：
回答by MJD
Objective C makes this operation relatively easy. Apple provides this documentation.
目标 C 使这个操作相对容易。Apple 提供了此文档。
To directly address your question, you are not calling a function, but a selector. Here is some sample code:
要直接解决您的问题，您不是在调用函数，而是在调用选择器。下面是一些示例代码：
Big Function:
大功能：
+ (void)theBigFunction:(SEL)func fromObject:(id) object{
[object preformSelector:func]
}
Then for class B:
然后对于B类：
- (void)littleBFunction {
NSLog(@"classB little function");
}
// somewhere else in the class
[ClassA theBigFunction:@selector(littleBFunction) fromObject:self]
Then for class C:
然后对于 C 类：
- (void)littleCFunction {
NSLog(@"classC little function");
}
// somewhere else in the class
[ClassA theBigFunction:@selector(littleCFunction) fromObject:self]
EDIT: Fix selectors sent (remove the semicolon)
编辑：修复发送的选择器（删除分号）
