0 
- (void)shootMissile {

  //Send missile to delegate for storage
  if ([delegate respondsToSelector:@selector(shootMissile)]) {
     [delegate performSelector:@selector(shootMissile)];
   }
}

委托函数意味着它委托给不同文件中的另一个函数。

我不确定我在javascript中遇到了类似的事情。

4

3 回答 3

2

根据这个问题的第二个答案，委托如何在 Objective-C 中工作？：

代表是一种设计模式；没有特殊的语法或语言支持。

这种模式当然可以在 Javascript 中使用，其中函数是一等对象，因此可以作为参数传递给其他函数。

要在 JS 中重写您的示例：

function shootMissile(selector) {
     if (selector.respondsTo(shootMissile)) {
         selector.perform(shootMissile);
     }
   }
}

大概“选择器”是一个具有两个功能属性（即方法）的对象，称为“respondsTo”和“perform”。

上述更自然（或至少更实用）的版本是：

function shootMissile(canShootMissile, fireMissile, missile) {
     if (canShootMissile(missile)) {
         fireMissile(missile);
     }
   }
}
于 2012-12-02T00:08:31.843 回答
1

First a correction of the following assumption:

"delegate function means it's delegate to another function in a different file."

1) forget the "file" thing, it's all about context (a class instance for example)

2) It does not delegate to other function : function is delegated to another context (in Javascript, access the context with "this" keyword)

So in javascript, given the following function:

var shootMissile = function () {
    this.missiles --;
};

We may delegate it to a bunch of different contexts (= objects), for example a boat:

var Boat = function () {
    this.missiles = 10 ;
},
boatInstance = new Boat () ;

Or a plane:

var Plane = function () {
    this.missiles = 5 ;
},
planeInstance = new Plane () ;

Finally the working example:

// planeInstance will have 4 missiles after call of delegated function
shootMissile.apply (planeInstance);

// boatInstance will have 9 missiles after call of delegated function
shootMissile.apply (boatInstance);

Hope this short explanation is sufficient for you.

于 2012-12-02T00:15:46.243 回答
1

等价物类似于匿名函数。我想也可以称为回调函数。

http://en.wikipedia.org/wiki/Anonymous_function#JavaScript

于 2012-12-01T23:51:52.370 回答