How I could get access to circles drawn in drawRect? - ios

Question

So, I have custom view, in which I draw 3 circles. How I could pass a "colorView" as an argument? Other man added all of this views from IB (not from code). And how could I change frames or visibility of these circles? Could I add variables for them? Thank you.
- (void)drawRect:(CGRect)rect
{
CGContextRef con = UIGraphicsGetCurrentContext();
CGContextSetFillColorWithColor(con, colorOfView.CGColor);
CGContextFillEllipseInRect(con, CGRectMake(0,10,85,85));
CGContextSetFillColorWithColor(con, [UIColor clearColor].CGColor);
CGContextSetBlendMode(con, kCGBlendModeClear); // erase
CGContextFillEllipseInRect(con, CGRectMake(62, -1, 35, 35));
CGContextSetFillColorWithColor(con, colorOfView.CGColor);
CGContextSetBlendMode(con, kCGBlendModeNormal);
CGContextFillEllipseInRect(con, CGRectMake(65,0,30,30));
}
Now for update color I use other method:
- (void)setCustomTitle:(NSString *)title andIcon:(NSString *)iconName andCircle:(UIColor *)color
{
self.titleLabel.text = title;
self.iconImage.image = [UIImage imageNamed:iconName];
colorOfView = color;
self.circleView.backgroundColor = color;
[self setNeedsDisplay];
}

Answer 1

You should create a property for your color:
#property (nonatomic, strong) UIColor *colorOfView;
And then change colorOfView = color to self.colorOfView = color
And change CGContextSetFillColorWithColor(con, colorOfView.CGColor); to CGContextSetFillColorWithColor(con, self.colorOfView.CGColor);

Answer 2

Expanding upon the answers/comments you have received already ...
The easy way of doing this which will definitely work
If you want to animate your circles, then you will need to call drawRec every 1/50th of a second or so. The way to do this is to use NSTimer to "wait" your loop between every frame. This can be in the ViewController or the View. After you draw your View, set up another NSTimer instance to wait another 20 milliseconds (not repeating). The delegate triggers a redraw (setNeedsDisplay), which then instantiates another NSTimer to wait another 20 milliseconds and so on. If you want the animation to stop, you don't instantiate another NSTimer.
Don't just keep calling setNeedsRefresh without a delay, or you will find your ViewController will become unresponsive as all CPU cycles will be spent refreshing. And it will run at very different speeds on different hardware.
As for how you gain access to the circle size etc in your ViewController, you have two choices. Firstly, you could possibly move the code which needs the circle size into drawRec in which case you would also handle the NSTimer instance (and delegate) in your View and your problem goes away.
Secondly, (and probably better) you could set up the circle sizes, colours etc as properties in your View .h file. Use Interface Builder (the storyboard) and the Assistant Editor to get a reference to your View class in your ViewController as an IBOutlet. You can then directly read or set these view properties from within your ViewController. (It is much easier to create a reference to your View in your ViewController than vice-versa). Your NSTimer will be in your ViewController, not your View.
If your circles are large, then you may be disappointed in the refresh rate.
The slightly harder but much faster way of doing most of this
As Dan pointed out, there may be a better way. You could set up your circles as the images in an ImageView (very similar to a View, but be aware that you cannot perform a drawRec against an ImageView). You can then animate the position, size, transparency and rotation by setting the frame of the UIImageView. The advantage is that this is far more efficient (the transformations are essentially done in hardware). For size, draw a large circle and scale down so you don't get jaggies. As far as I know, you can't directly change the colour, but you can probably set up a cut-out in the shape of a circle and use it as a mask against a rectangle which you use memset (or something fast) to fill in the correct colour. This is pretty complicated to do, if you need to change colours I would definitely try option 1 first. You should read https://developer.apple.com/library/ios/qa/qa1708/_index.html to see how this option works in general and why it is better than Option 1.
So in summary I would try Option 1 first, and see if it is fast enough to give you smooth animation. If it doesn't, try Option 2 which (apart from changing colours) is easier than it probably sounds.
Good luck