How to Subclass UIView and then how to use it with drawRect to draw graphics?

Question

How to Subclass UIView and then how to use it with drawRect to draw graphics? Do I need to add the framework and then include in the header file QuartzCore or any other?

---

Combined solutions:

---

#import <UIKit/UIKit.h>
@interface drawingViewController : UIViewController {
}
@end

---

#import "drawingViewController.h"
#import "myview.h"
@implementation drawingViewController
- (void)viewDidLoad {
    [super viewDidLoad];

    CGRect rect = CGRectMake(0,0,340,480);  
    myview *ui = [[myview alloc] initWithFrame:rect];
    [self.view addSubview:ui];
}

---

#import <UIKit/UIKit.h>
@interface myview : UIView {
}
@end

---

#import "myview.h"
@implementation myview
- (id)initWithFrame:(CGRect)frame {
    self = [super initWithFrame:frame];
    if (self) {
        // Initialization code.
    }
    return self;
}


// Only override drawRect: if you perform custom drawing.
// An empty implementation adversely affects performance during animation.
- (void)drawRect:(CGRect)rect {
    // Drawing code.
    CGContextRef context = UIGraphicsGetCurrentContext();

    CGContextAddArc(context, 50, 50, 50, 0, 30, 0);
CGContextFillPath(context);

    //set the fill or stroke color
    CGContextSetRGBFillColor(context, 1, 0.5, 0.5, 1.0);
    CGContextSetRGBStrokeColor(context, 0.5, 1, 0.5, 1.0);

    //fill or draw the path
    CGContextDrawPath(context, kCGPathStroke);
    CGContextDrawPath(context, kCGPathFill);

    ------------------------------
    CGContextAddArc(context, 100, 100, 20, 0, 30, 0);

    //set the fill or stroke color
    CGContextSetRGBFillColor(context, 1, 0.5, 0.5, 1.0);
    CGContextSetRGBStrokeColor(context, 0.5, 1, 0.5, 1.0);

    //fill or draw the path
    CGContextDrawPath(context, kCGPathStroke);
    CGContextDrawPath(context, kCGPathFill);

}

---

other things to note:

Drawing triangle/arrow on a line with CGContext

CGContext Optimization

iPhone clear CGContext

Saving and restoring CGContext

How do I draw a line on the iPhone?

How to draw string in other device orientations using CGContext iOS

Answer 1

in .h file

#import <QuartzCore/QuartzCore.h>
@interface YourView : UIView {

...

in .m file

- (void)drawRect:(CGRect)rect{
    CGContextRef ctx = UIGraphicsGetCurrentContext();
    //your drawings
}

then call setNeedsDisplay to redraw the rect