Objective-C: message syntax vs. dot syntax; what's the difference?

问题

If I'm using @synthesize foo;, what's the difference between the following:

// message syntax
[myObj setFoo:5];
[myObj foo];

and

// dot syntax
myObj.foo = 5;
myObj.foo;

I like the consistency of the dot syntax but I don't know if it's doing something I should be I concerned about.

Any additional information would be a great help.

回答1:

There is no functional difference between using dot syntax and using message syntax.

I find that using message syntax is more consistent with the language as a whole and that dot syntax was just implemented as a convenience to programmers who were coming over from languages that used it (Java comes to mind).

All I ask is: Whichever one you choose, be consistent with it. Do not mix and match single property setters! (Multiple-argument setters are obviously exempt).

回答2:

They are the same.

The dot syntax is used to signify the access of @property's which you can also acces via:

[myObject setValue: [NSNumber numberWithIntValue:5] forKey:@"foo"];
[myObject valueForKey:@"foo"];

But in essence the calls are the same.

来源：https://stackoverflow.com/questions/4259946/objective-c-message-syntax-vs-dot-syntax-whats-the-difference