Objective C中message，method和selector等的区别和联系

   selector是方法名，message包括selector和方法的参数，method包括selector和方法的具体实现。

 

以下转自stackoverflow: http://stackoverflow.com/questions/5608476/whats-the-difference-between-a-method-and-a-selector

 

• Selector - a Selector is the name of a method. You're very familiar with these selectors: alloc,init, release, dictionaryWithObjectsAndKeys:, setObject:forKey:, etc. Note that the colon is part of the selector; it's how we identify that this method requires parameters. Also (though it's extremely rare), you can have selectors like this: doFoo:::. This is a method that takes three parameters, and you'd invoke it like [someObject doFoo:arg1 :arg2 :arg3]. There's no requirement that there be letters before each part of the selector components. As I said, this is extremely rare, and you will not find it used in the Cocoa frameworks. You can work with selectors directly in Cocoa. They have the type SEL: SEL aSelector = @selector(doSomething:) or SEL aSelector = NSSelectorFromString(@"doSomething:");

• Message - a message is a selector and the arguments you are sending with it. If I say[dictionary setObject:obj forKey:key], then the "message" is the selectorsetObject:forKey: plus the arguments obj and key. Messages can be encapsulated in anNSInvocation object for later invocation. Messages are sent to a receiver. (ie, the object that "receives" the message).

• Method - a method is a combination of a selector and an implementation (and accompanying metadata). The "implementation" is the actual block of code; it's a function pointer (an IMP). An actual method can be retrieved internally using a Method struct (retrievable from the runtime).