Loading a UIView subclass from NIB size issues

问题:

I have a subclass of UIView that needs to calculates it's height according to it's width. When created in code everything works. However when I try to create the view in Interface builder, and although I override all related methods, I can't get the size of the view set in interface builder.

- (id)initWithCoder:(NSCoder *)aDecoder
{
    NSLog(@"init with coder before super width %d",super.frame.size.width); // returns 0
    self = [super initWithCoder:aDecoder];
    NSLog(@"init with coder after super width %d",super.frame.size.width); // still returns 0
}

- (void) awakeFromNib
{
      NSLog(@"width of view %d",super.frame.size.width); // Returns 0 as well
}

- (void) setFrame:(CGRect)aFrame
{
    [super setFrame:aFrame]; // Called from initWithCoder by super. Correct frame size. 
}  

So my next guess was the maybe the superview of my view is setting my view's frame after awakeFromNib. Well it turns out it doesnt. I overrided setFrame on my view, and it is called during initWithCoder.

So this is what I know so far:

1. First initWithCoder is called
2. During initWithCoder a call to setFrame:(CGRect)aFrame is sent
3. in setFrame the size of the frame is correct, and I call [super setFrame:aFrame]
4. awakeFromNib is called
5. super.frame.size.width = 0 in awakeFromNib self.frame.size.width is also 0
6. When the process is done, it seems that the view is a few pixels below where it's suppose to be, but I guess my code get so massed up with the dimensions that it might be something I do.

Any help will be appreciated

回答1:

If you extend initWithCoder, be sure to call the super method. It is during this super call that setFrame will be called on your class.

You can then re-use your standard initWithFrame call.

I always do the following:

- (id)initWithCoder:(NSCoder *)aDecoder {
    self = [super initWithCoder:aDecoder]; // Required. setFrame will be called during this method.
    return [self initWithFrame:[self frame]];
}