Performance difference between dot notation versus method call in Objective-C

Question

You can use a standard dot notation or a method call in Objective-C to access a property of an object in Objective-C.

myObject.property = YES;

Answer 1

Dot notation for property access in Objective-C is a message send, just as bracket notation. That is, given this:

@interface Foo : NSObject
@property BOOL bar;
@end

Foo *foo = [[Foo alloc] init];
foo.bar = YES;
[foo setBar:YES];

The last two lines will compile exactly the same. The only thing that changes this is if a property has a getter and/or setter attribute specified; however, all it does is change what message gets sent, not whether a message is sent:

@interface MyView : NSView
@property(getter=isEmpty) BOOL empty;
@end

if ([someView isEmpty]) { /* ... */ }
if (someView.empty) { /* ... */ }

Both of the last two lines will compile identically.