Question

What happens if I create a property with “assign” attribute set the property to nil in dealloc method

@property (nonatomic, assign) NSString* myData;

- (void)dealloc {
    self.myData = nil;
}

Answer 1

then the setter is called which just sets the pointer to nil and nothing else happens.

edit: difference between (nonatomic, assign) and (nonatomic, retain)

An assign-property will only set the pointer and a retain-property will also call release on the old and retain on the new object.

The synthesized (nonatomic, assign)-setter will look like this:

-(void) setMyData:(NSString*)value
{
    myData = value; //just assigning the pointer
}

And the synthesized (nonatomic, retain)-setter will look like this:

-(void) setMyData:(NSString*)value
{
    [value retain];   // retain new object
    [myData release]; // release old object. if myData is nil: nothing happens
    myData = value;   // assigning the pointer
}

Between the getters there is no difference. Both are just nonatomic.