drawRect not getting called from setNeedsDisplay - ios

Question

I have recently started learning core graphics to draw on views, but every time I call setNeedsDisplay, the method runs but doesn't trigger drawRect. In my project, I have a view on a view controller. The view contains an if statement in drawRect that checks if a BOOL variable is YES or NO. If YES, it uses the code to draw a red circle. If NO, it draws a blue circle. In the BOOL's setter, it calls setNeedsDisplay. I create an instance of this view class in the ViewController and set the BOOL but the view is not redrawing. Why is the method not getting called? I posted the xcode files and code bits below.
Customview.m:
#import "CustomView.h"
#implementation CustomView
- (id)initWithFrame:(CGRect)frame
{
self = [super initWithFrame:frame];
if (self) {
[self setup];
}
return self;
}
-(void)awakeFromNib{
[self setup];
}
-(void)setup{
_choice1 = YES;
}
-(void)setChoice1:(BOOL)choice1{
_choice1 = choice1;
[self setNeedsDisplay];
}
// Only override drawRect: if you perform custom drawing.
// An empty implementation adversely affects performance during animation.
- (void)drawRect:(CGRect)rect
{
if (_choice1) {
UIBezierPath * redCircle = [UIBezierPath bezierPathWithOvalInRect:rect];
[[UIColor redColor]setFill];
[redCircle fill];
}else if (!_choice1){
UIBezierPath * blueCircle = [UIBezierPath bezierPathWithOvalInRect:rect];
[[UIColor blueColor]setFill];
[blueCircle fill];
}
}
#end
CustomView.h:
#import <UIKit/UIKit.h>
#interface CustomView : UIView
#property (nonatomic) BOOL choice1;
#end
ViewController.m:
#import "ViewController.h"
#import "CustomView.h"
#interface ViewController ()
- (IBAction)Change:(id)sender;
#end
#implementation ViewController
- (void)viewDidLoad
{
[super viewDidLoad];
// Do any additional setup after loading the view, typically from a nib.
}
- (void)didReceiveMemoryWarning
{
[super didReceiveMemoryWarning];
// Dispose of any resources that can be recreated.
}
- (IBAction)Change:(id)sender {
CustomView * cv = [[CustomView alloc]init];
[cv setChoice1:NO];
}
#end
Full project: https://www.mediafire.com/?2c8e5uay00wci0c
Thanks

Answer 1

You need to create an outlet for your CustomView in your ViewController. Delete the code that creates the new CustomView instance and use _cv to refer to the customView.
#interface ViewController ()
- (IBAction)Change:(id)sender;
#property (weak,nonatomic) IBOutlet CustomView *cv;
#end
Then, in the storyboard, connect ViewController's cv outlet to the CustomView. Also, you'll need to implement the initFromCoder: method on CustomView.
- (id)initWithCoder:(NSCoder *)aDecoder {
if ((self = [super initWithCoder:aDecoder])) {
[self setup];
}
return self;
}