Passing parameters to drawRect

Question

I have a couple of UIView classes all drawing the same thing but in different colors and alpha settings. I've tried to pass parameters but cannot figure out how to get the drawRect part where I need to be.

I draw like this:

CGRect positionFrame = CGRectMake(widthCoordinate,heightCoordinate,20.9f,16.5f);
DrawHexBlue *hex = [[DrawHexBlue alloc] initWithFrame:positionFrame];
[self.imageView addSubview:hex];

My DrawHexBlue class is this:

- (id)initWithFrame:(CGRect)frame{
self = [super initWithFrame:frame];
if (self)
{
    [self setOpaque:YES];
    [self setBackgroundColor:[UIColor clearColor]];
}
return self;

}

- (void)drawRect:(CGRect)rect{    
UIBezierPath *aPath = [UIBezierPath bezierPath];
[[UIColor whiteColor] setStroke];
[[UIColor blueColor] setFill];

// Set the starting point of the shape.
[aPath moveToPoint:CGPointMake(7, 0)];

// Draw the lines.
[aPath addLineToPoint:CGPointMake(16.2, 0)];
[aPath addLineToPoint:CGPointMake(20.9, 8.7)];
[aPath addLineToPoint:CGPointMake(16.2, 16.5)];
[aPath addLineToPoint:CGPointMake(6.7, 16.5)];
[aPath addLineToPoint:CGPointMake(2.1, 8.7)];
[aPath closePath];

[aPath setLineWidth:1.0f];
[aPath fillWithBlendMode:kCGBlendModeNormal alpha:0.75];
[aPath stroke];
}

I create a new class for every new color I need and new alpha value. Surely there has to be a better way to use one class and just change parameters/values...?

Answer 1

Create a single UIView subclass and add properties:

@interface YourView : UIView

@property (nonatomic, strong) UIColor *strokeColor;
@property (nonatomic, strong) UIColor *fillColor;

@end

Then in drawRect: you can access this property:

- (void)drawRect:(CGRect)rect{    
    UIBezierPath *aPath = [UIBezierPath bezierPath];
    [self.strokeColor setStroke];
    [self.fillColor setFill];

And you can set it on the view when you create it:

YourView *hex = [[YourView alloc] initWithFrame:positionFrame];
hex.strokeColor = [UIColor whiteColor];
hex.fillColor = [UIColor blueColor];

Answer 2

Yes.

Use properties.

The view that does the drawing should have these lines of code in its header file:

@property (nonatomic, strong) UIColor *colorToDraw;

- (id)initWithFrame:(CGRect)frame color:(UIColor *)color;

And your init method should look like:

- (id)initWithFrame:(CGRect)frame color:(UIColor *)color
{
    self = [super initWithFrame:frame];
    if (self)
    {
        [self setOpaque:YES];
        [self setBackgroundColor:[UIColor clearColor]];
        self.colorToDraw = color;
    }
    return self;
}

With a drawRect of:

- (void)drawRect:(CGRect)rect{    
    UIBezierPath *aPath = [UIBezierPath bezierPath];
    [[UIColor whiteColor] setStroke];
    [self.colorToDraw setFill];

    // Set the starting point of the shape.
    [aPath moveToPoint:CGPointMake(7, 0)];

// Draw the lines.
    [aPath addLineToPoint:CGPointMake(16.2, 0)];
    [aPath addLineToPoint:CGPointMake(20.9, 8.7)];
    [aPath addLineToPoint:CGPointMake(16.2, 16.5)];
    [aPath addLineToPoint:CGPointMake(6.7, 16.5)];
    [aPath addLineToPoint:CGPointMake(2.1, 8.7)];
    [aPath closePath];
    
    [aPath setLineWidth:1.0f];
    [aPath fillWithBlendMode:kCGBlendModeNormal alpha:0.75];
    [aPath stroke];
}

Now, you can draw like this:

CGRect positionFrame = CGRectMake(widthCoordinate,heightCoordinate,20.9f,16.5f);   
DrawHexBlue *hex = [[DrawHexBlue alloc] initWithFrame:positionFrame color:[UIColor orangeColor]]; //Or whatever.
[self.imageView addSubview:hex];

You might want to change your subclass's name to something that doesn't imply it draws blue, though.