How to update/redraw UIView

Question

I have a UIView, in the view's drawRect method I am using CGRect to draw lines and UILabel to draw a label onto the view.

I would like to change the color of the lines once the view is touched. When the view is touched, it notifies my ViewController that there was a touch:

- (void)touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event
{
    [self.controller viewTouched:self];
}

My ViewController responds by removing the view from the superview, creating a new UIView, and setting any necessary properties, including a new color for the lines, and re-adding the view to the superview:

-(void)redrawView:(SomeView *)view asSelected:(BOOL)selected
{
    [view removeFromSuperview];
    SomeView *newView = [[SomeView alloc] initWithFrame:view.frame];
    newView.tintColor =  (selected) ? [UIColor blueColor] : [UIColor redColor];
    newView.controller = self;
    [self.scrollView addSubview:newView];
}

The problem I am having is the UILabel never gets removed from the UIView. It keeps drawing a new UILabel on top of the old one(s).

Am I redrawing the view correctly? Am I redrawing the view in the most efficient manner? What is it that I do not understand about redrawing views?

Your help is much appreciated.

Answer 1

Try to place redrawView method code inside the drawRect in your UIView class.

- (void)touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event
{
    [self.controller viewTouched:self]; // ask to refresh your view inside viewTouched 
                                        // by calling [self setNeedsDisplay:YES]; there
}