iPhone SDK: How to trigger drawRect on UIView subc

问题:

I am subclassing a UIView and overwrite the drawRect method. I'm noticing that the view's drawrect is only being called when the view first loads. After that it is never called again. How to I make sure it gets called after an orientation change? I've tried calling setNeedsDisplay on the view before and after the rotation and that doesn't do it.

回答1:

[myView setContentMode:UIViewContentModeRedraw];

You can set this in IB as well (i.e., set mode to "redraw")

回答2:

This was a bug related to something completely different. setNeedsDisplay does indeed cause drawRect to be called.

回答3:

to answer this and the other 94,000 similiar questions about view rotation/drawrect funkiness,

-(id)initWithFrame:(CGRect)frame
{
    if(self=[super initWithFrame:frame]) {
        self.autoresizesSubviews=YES;
        self.autoresizingMask=UIViewAutoresizingFlexibleWidth|UIViewAutoresizingFlexibleHeight;
    }
    return self;
}