UIView With Multiple DrawRect Methods - ios

Question

I'm currently trying to create a Grid/Cinematic Overlay with a UIView.
I created a few methods; drawVerticalLine and Horizontal Lines and stuff...
I have a UIViewController that inits the UIGridView. I can put all my methods in the draw rect and draw them all at once.
However, I want to be able to call them individually from the ViewController. When I try to doenter code here that. I get an ": CGContextDrawPath: invalid context 0x0" Code Below.
From my ViewController I want to be able to call "drawGrid :withColor :andLines;" Or something
-
(void)drawRect:(CGRect)rect
{
if (self.verticalLinesON == YES) {
[self drawVerticalLinesForGrid:100 :[UIColor redColor] :[UIColor greenColor]];
}
[self show16NineOverLay:[UIColor orangeColor]];
[self show4ThreeOverLay:[UIColor orangeColor]];
[self drawHorizontalLinesForGrid:100 :[UIColor blueColor] :[UIColor yellowColor]];
}
-(void)drawVerticalLinesForGrid:(float)sectionsVertically :(UIColor *)lineColor1 :(UIColor *)lineColor2
{
CGContextRef context = UIGraphicsGetCurrentContext();
CGContextSetLineWidth(context, 2);
int i = 0;
float amountOfSectionsVertically = sectionsVertically;
for (i = 1; i < amountOfSectionsVertically; i++)
{//Horizontal Lines first.
float xCoord = self.frame.size.width * ((i+0.0f)/amountOfSectionsVertically);
CGContextMoveToPoint(context, xCoord, 0);
CGContextAddLineToPoint(context, xCoord, self.frame.size.height);
if (i%2 == 1)
{//if Odd
CGContextSetStrokeColorWithColor(context, lineColor1.CGColor);
}
else if(i%2 == 0)
{//if Even
CGContextSetStrokeColorWithColor(context, lineColor2.CGColor);
}
CGContextStrokePath(context);
}
}
-(void)drawHorizontalLinesForGrid :(float)sectionsHorizontally :(UIColor *)lineColor1 :(UIColor *)lineColor2
{
CGContextRef context = UIGraphicsGetCurrentContext();
CGContextSetLineWidth(context, 2);
int i = 0;
float amountOfSectionsHorizontally = sectionsHorizontally;
for (i = 1; i < amountOfSectionsHorizontally; i++)
{//Vertical Lines first.
float yCoord = self.frame.size.height * ((i+0.0f)/amountOfSectionsHorizontally);
CGContextMoveToPoint(context, 0, yCoord);
CGContextAddLineToPoint(context, self.frame.size.width, yCoord);
if (i%2 == 1)
{//if Odd
CGContextSetStrokeColorWithColor(context, lineColor1.CGColor);
}
else if(i%2 == 0)
{//if Even
CGContextSetStrokeColorWithColor(context, lineColor2.CGColor);
}
CGContextStrokePath(context);
}
}
-(void)show16NineOverLay:(UIColor *)lineColor
{
CGContextRef context = UIGraphicsGetCurrentContext();
CGContextSetLineWidth(context, 10);
//x/y
float yCoord = (0.5) * (self.frame.size.height * (1.778)

Answer 1

What you should do is set some state on your grid view class that specifies what should be drawn (just vertical, just horizontal, both, etc) and then call setNeedsDisplay on the view.
This will trigger a call to drawRect:. Then your drawRect: method should look at its current state and call just the appropriate methods to draw the desired parts.
You must never directly call drawRect: on a view.