Can't clear the entire drawing from the screen.

[edwardinubuntu]

The user can shake the iPhone or press erase button, still can't clear the entire drawing from the screen.

After calling the resetView, self setNeedsDisplay will calling into drawRect method, but int the drawRect function haven't implement the clear the drawing yet.

- (void)resetView {
    [squiggles removeAllObjects];
    [finishedSquiggles removeAllObjects];
    [self setNeedsDisplay]; // refresh the display
}

// An empty implementation adversely affects performance during animation.
- (void)drawRect:(CGRect)rect {
    // Drawing code.
    CGContextRef context = UIGraphicsGetCurrentContext();
    
    for (Squiggle *squiggle in finishedSquiggles)
        [self drawSquiggle:squiggle inContext:context];
    
    for (NSString *key in squiggles) {
        Squiggle *squiggle = [squiggles valueForKey:key];
        [self drawSquiggle:squiggle inContext:context];
    }
}

[edwardinubuntu]

After remove unwanted UIView, and use the original MainView instead. The bug fixed after tested.