Question

I don’t know how to draw corner grab indicators in drawRect method.this is mycode:

- (void)drawRect:(CGRect)rect{
CGContextRef context = UIGraphicsGetCurrentContext();
CGContextSetStrokeColorWithColor(context, [UIColor whiteColor].CGColor);
CGContextSetLineWidth(context, 0.8f);

CGFloat colX1 = CGRectGetMaxX(rect)/3.0;
CGFloat colX2 = 2*colX1;
CGFloat rowY1 = CGRectGetMaxY(rect)/3.0;
CGFloat rowY2 = 2*rowY1;

CGContextBeginPath(context);
CGContextMoveToPoint(context, colX1, CGRectGetMinY(rect));  
CGContextAddLineToPoint(context, colX1, CGRectGetMaxY(rect));

CGContextMoveToPoint(context, colX2, CGRectGetMinY(rect));
CGContextAddLineToPoint(context, colX2, CGRectGetMaxY(rect));

CGContextMoveToPoint(context, CGRectGetMinX(rect),rowY1);
CGContextAddLineToPoint(context, CGRectGetMaxX(rect),rowY1);

CGContextMoveToPoint(context, CGRectGetMinX(rect),rowY2);
CGContextAddLineToPoint(context,CGRectGetMaxX(rect),rowY2);

CGContextStrokePath(context);}

and in the init method :

 CATiledLayer *tiledLayer = (CATiledLayer *)[self layer];
    tiledLayer.levelsOfDetail = 4;
    self.layer.borderColor = [UIColor whiteColor].CGColor;
    self.layer.borderWidth = 1.5;

my screenshot is:

I want to know how to draw my view like this:

I really want to know the code to draw the corner grab indicators.

Thanks in advance!

Answer 1

The corners are just 8 extra lines drawn just to the outside of the box you’re drawing. Inset your box a little bit and draw them at the corners of the frame. You need to draw the outside box in that case rather than using borderWidth. But it’s just more CGContextMoveToPoint / CGContextAddLineToPoint calls. You seem to understand all the tools that you need already.

EDIT BTW, if you look carefully at the picture you posted, you’ll note that the border is actually made of both black and white pixels. They may have drawn a white border with a width of 2 and then come back and drawn the 4 black lines along the edges. This could be a little easier to draw.