Do private ivars in Objective-C have atomic attribute by default (like properties)?

Question

Consider a scenario where I have some instance variable like this.

@implementation Foo {
    NSString *foo;
}

// Some code 

@end

I wanted

Answer 1

I wanted to know if this foo ivar would be atomic by default

No, it would not. That is one of the (many) reasons for using a @property declaration instead of an ivar. With a @property declaration, you get an actual accessor method written for you behind the scenes, and this will be atomic by default.