Placement of [super methodName];

I've seen this done both ways, with the [super methodName]; as the first line in a method and as the last line. Is there a best way to do this?

For example:

- (void)viewDidLoad {

    [super viewDidLoad];
    self.intX = 1;
}

- (void)viewDidLoad {

    self.intX = 1;
    [super viewDidLoad];

}

- (void)dealloc {

    [myControl release];
开发者_如何转开发    [super dealloc];
}

In general, when dealing with views you want to take into account the standard behaviour in relation to the changes that your subclass will take.

This is best illustrated with

- (void)drawRect:(NSRect)dirtyRect

Effectively you are drawing your view into the rect but the view itself is doing all of the highlighting and sub view management in there as well.

So, do you need to do something that will occur before or after the super class does it's normal behaviour?

In these cases it is best to test by moving your code before and after the super call. It may also yield some behaviour understanding by not even making the super call to see how it affects what is done.

viewDidLoad is more of an initialiser and typically is more relevant to your subclassed ivars than the actual class itself. If however your subclassed viewDidLoad is affecting the ivars or state of the subclassed view; you likely want to wait until after super so that your changes are't blown away.

In dealloc we call [super methodName]; at last, because before releasing super class you need to clean up child class objects, otherwise they will become orphans.

For example:

Just think about this example. will it make sense to you ?

You will use your dad's money for to get a good education then you will start earning (In your question, get superclass's benifits before you create your own subclass). At your bad time, first you will loose your money and slowly you may drain your dad's money too (In dealloc method, release subclass's object then super class).