Drawing in Quartz 2D by pushing a button - objective-c

Question

I'm a little bit nooby in Objective-C and I just started working with Quartz 2D. My problem is very simple: I want to draw in Quartz 2D by pressing button. I don't know how I can do that because there are two different classes in my project. I used that tutorial: http://www.techotopia.com/index.php/An_iOS_7_Graphics_Tutorial_using_Core_Graphics_and_Core_Image
Here is my code:
ViewController.h
#interface ViewController : UIViewController
- (IBAction)Start;
ViewController.m
- (IBAction)Start {
}
Draw2D.h
#import <UIKit/UIKit.h>
#interface Draw2D : UIView
#end
Draw2D.m
- (id)initWithFrame:(CGRect)frame
{
self = [super initWithFrame:frame];
if (self) {
// Initialization code
}
return self;
CGContextRef context = UIGraphicsGetCurrentContext();
CGContextSetLineWidth(context, 2.0);
CGColorSpaceRef colorspace = CGColorSpaceCreateDeviceRGB();
CGFloat components[] = {0.0, 0.0, 1.0, 1.0};
CGColorRef color = CGColorCreate(colorspace, components);
CGContextSetStrokeColorWithColor(context, color);
CGContextMoveToPoint(context, 30, 30);
CGContextAddLineToPoint(context, 300, 400);
CGContextStrokePath(context);
CGColorSpaceRelease(colorspace);
CGColorRelease(color);
}
- (void)drawRect:(CGRect)rect {
CGContextRef context = UIGraphicsGetCurrentContext();
CGContextSetLineWidth(context, 4.0);
CGContextSetStrokeColorWithColor(context,
[UIColor blueColor].CGColor);
CGRect rectangle = CGRectMake(60,170,200,80);
CGContextAddRect(context, rectangle);
CGContextStrokePath(context);
}

Answer 1

If you want to show Draw2D view upon pressing a button, you can add draw2DView as subview of your ViewController:
/// ViewController
- (IBAction)Start:(UIButton *)sender
{
[self.view addSubview:draw2DView];
}
and you should remove these lines in your Draw2D initWithFrame method
CGContextRef context = UIGraphicsGetCurrentContext();
CGContextSetLineWidth(context, 2.0);
CGColorSpaceRef colorspace = CGColorSpaceCreateDeviceRGB();
CGFloat components[] = {0.0, 0.0, 1.0, 1.0};
CGColorRef color = CGColorCreate(colorspace, components);
CGContextSetStrokeColorWithColor(context, color);
CGContextMoveToPoint(context, 30, 30);
CGContextAddLineToPoint(context, 300, 400);
CGContextStrokePath(context);
CGColorSpaceRelease(colorspace);
CGColorRelease(color);
They are below return self; therefore will not be triggered.