Question

I am trying to draw a circle after clicking a button. I can create a rectangle but cannot draw a circle.

Is there a way to make this:

-(IBAction) buttonTouched 
{
}

call or signal this to work:

- (void)drawRect:(CGRect)rect 
{ 
}

Thanks for any input!

*Edit**
Sorry, it’s not working. Not sure what I’m doing wrong:

1) Created a new view-based project named “test”.
2) Created a Objective-C class UIView named “view”.
3) In IB dragged a button onto the view, linked it to “buttonTouched” – Touched Up Inside.

testViewController.h
#import <UIKit/UIKit.h>
#import "view.h"
@interface testViewController : UIViewController {
}
-(IBAction) buttonTouched;
@end


testViewController.m
#import "testViewController.h"
#import "view.h"
@implementation testViewController
- (IBAction)buttonTouched {
    [[self view] setNeedsDisplay];
}

view.m

#import "view.h"

@implementation view

- (id)initWithFrame:(CGRect)frame {    
   self = [super initWithFrame:frame];
    if (self) {
    }
    return self;
}

- (void)drawRect:(CGRect)rect {
    CGContextRef contextRef = UIGraphicsGetCurrentContext();

    CGContextFillEllipseInRect(contextRef, CGRectMake(100, 100, 25, 25));
    CGContextSetRGBFillColor(contextRef, 0, 0, 255, 1.0);

    CGContextStrokeEllipseInRect(contextRef, CGRectMake(100, 100, 25, 25));
    CGContextSetRGBFillColor(contextRef, 0, 0, 255, 1.0);
}


- (void)dealloc {
    [super dealloc];
}

@end

Answer 1

This should do what you want it to. Check Sample code

     // The color is by this line CGContextSetRGBFillColor( context , red , green , blue , alpha);


     // Draw a circle (filled)
     CGContextFillEllipseInRect(contextRef, CGRectMake(100, 100, 25, 25));
     CGContextSetRGBFillColor(contextRef, 0, 0, 255, 1.0);

     // Draw a circle (border only)
     CGContextStrokeEllipseInRect(contextRef, CGRectMake(100, 100, 25, 25));
     CGContextSetRGBFillColor(contextRef, 0, 0, 255, 1.0);