有人可以解释这个 Objective-C 方法声明语法吗 [英] Can somebody explain this Objective-C method declaration syntax

问题描述

我正在阅读一本 iPhone 开发书*，但并不真正了解 Objective C.在大多数情况下，我能够了解正在发生的事情，但有一些方法声明如下所示，我有一个解析有点麻烦.例如:

I'm working through an iPhone development book* without really knowing Objective C. For the most part I'm able to follow what's going on, but there are a few method declarations like the one below that I'm having a bit of trouble parsing. For example:

- (NSInteger)tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger) section {
  return [self.controllers count]; //controllers is an instance variable of type NSArray in this class
}

看起来这是一个名为numberOfRowsInSection的方法，它返回一个NSInteger，并以一个NSInteger作为参数，在本地称为'section'.但我不明白所有对 tableView 的引用，或者为什么当它没有在方法中使用时需要一个参数.有人可以澄清这一点吗?谢谢.

It looks this is a method called numberOfRowsInSection, and it returns an NSInteger, and takes an NSInteger as a parameter which is locally called 'section'. But I don't understand all the references to tableView, or why this takes a parameter when it is not used within the method. Can somebody clarify this? Thanks.

*p.258，开始 iPhone 3 开发，Mark 和 LaMarche，Apress 出版

*p. 258, Beginning iPhone 3 Development, by Mark and LaMarche, published by Apress

更新:我找到了另一个更详细的 SO 线程:Objective C 中的方法语法

Update: I was able to find another SO thread that goes into a bit more detail: Method Syntax in Objective C

推荐答案

这是一个方法叫做:

tableView:numberOfRowsInSection:

它需要两个参数:

• a UITableView*
• 一个 NSInteger

该方法还采用一个隐式的 self 参数，即调用它的实例.正如 Dreamlax 所指出的，它还需要一个隐式 _cmd，这是当前被调用的方法.

The method also takes an implicit self parameter , which is the instance it is called with. As dreamlax notes, it also takes an implicit _cmd, which is the method that currently gets invoked.

正如 Mark 所说，如果您符合某个接口，则不使用某些参数是完全常见的.

As Mark says, it is completely common to not use certain parameters if you are conforming to a certain interface.

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