Creating a UIBezierPath in UIView Category. not being shown

Question

I am trying to create a triangle using UIBezierPath in a category of UIView. but the triangle is not being shown. also getting an : CGContextSetFillColorWithColor. So my question is how to make triangle or any path using a category of UIView. Demo Project

#import "UIView+Bubble.h"
#import <QuartzCore/QuartzCore.h>

@implementation UIView (Bubble)

+(UIView *)makeBubble{
    UIView *customView = [[UIView alloc] init];
    customView.frame=CGRectMake(0, 0, 320, 500);
    UIBezierPath *triangle = [UIBezierPath bezierPath];
    [triangle moveToPoint:CGPointMake(100, 0)];
    [triangle addLineToPoint:CGPointMake(0, 100)];
    [triangle addLineToPoint:CGPointMake(200, 100)];
    [triangle closePath];
    [[UIColor blackColor] setFill];
    [triangle fill];
    customView.layer.shadowPath = [triangle CGPath];
    return customView;
}
@end

In ViewController.m using it like:-

- (void)viewDidLoad
{
    UIView *helpBubble=[UIView makeBubble];
    [self.view addSubview:helpBubble];
}

Answer 1

In your UIView+Bubble.h category UIBezierPath tries to draw triangle on a null context. If you want to draw shape using UIBezierPath like above, you have to put this code inside drawRectmethod of a View class.

On the other hand, you could create a new context to draw. You may modify your makeBubble method as follow:

+(UIView *)makeBubble{
   // declare UIimageView, not UIView
   UIImageView *customView = [[UIImageView alloc] init];
   customView.frame=CGRectMake(0, 0, 320, 500);

   // create a new contex to draw
   UIGraphicsBeginImageContextWithOptions(CGSizeMake(200, 200), NO, 0);

   UIBezierPath *triangle = [UIBezierPath bezierPath];
   [triangle moveToPoint:CGPointMake(100, 0)];
   [triangle addLineToPoint:CGPointMake(0, 100)];
   [triangle addLineToPoint:CGPointMake(200, 100)];
   [triangle closePath];
   [[UIColor blackColor] setFill];
   [triangle fill];

   customView.image = UIGraphicsGetImageFromCurrentImageContext();

   UIGraphicsEndImageContext();

   return customView;
}

EDIT:

to make it dynamic you could pass a cgRect argument, like

+(UIView *)makeBubble:(CGRect)rect

also change to customView.frame=rect; and UIGraphicsBeginImageContextWithOptions(rect.size, NO, 0); inside this method. And call makeBubble:(CGRect)rect method as

UIView *helpBubble=[UIView makeBubble:/*your desire rect*/];

P.S. it will be great if you calculate the points depending on the rect too.