Calling setNeedsDisplay in layoutSubviews?

问题

Consider a view with a custom background that is drawn in drawRect:. If the view changes size, the background need to be redrawn.

Is this a bad idea?

- (void) layoutSubviews
{
    [super layoutSubviews];
    [self setNeedsDisplay];
}

If it is, what would be a better alternative considering I can't control who changes the size of the view?

回答1:

Dont do that, it's not necessary. Set the contentMode of the view to UIViewContentModeRedraw:

UIViewContentModeRedraw

Redisplays the view when the bounds change by invoking the setNeedsDisplay method. Available in iOS 2.0 and later. Declared in UIView.h.

This will achieve the same effect.

来源：https://stackoverflow.com/questions/13434794/calling-setneedsdisplay-in-layoutsubviews