iPhone init 方法返回类型

Question

假设我们正在 iPhone 程序中编写一个类(我们称之为 Class)。在所有示例中，init 方法通常是这样声明的:

-(id) initWithFoo: (Foo *) foo

我的问题是:执行以下操作会更合乎逻辑吗？为什么或为什么不？

-(Class *) initWithFoo: (Foo *) foo

Answer 1

来自Implementing an Initializer在 Mac 开发中心

The reason for this is that id gives an indication that the class is purposefully not considered—that the class is unspecified and subject to change, depending on context of invocation. For example, NSString provides a method initWithFormat:. When sent to an instance of NSMutableString (a subclass of NSString), however, the message returns an instance of NSMutableString, not NSString. (See also, though, the singleton example given in “Combining Allocation and Initialization.”)