setting a background color of an UIView from an UIViewController

Question

I have a UIView subclass that draws a simple rectangle with this code:

- (void)drawRect:(CGRect)rect {

//Get the CGContext from this view
CGContextRef context = UIGraphicsGetCurrentContext();

CGColorRef myColor = [UIColor colorWithHue:0 saturation:1 brightness:0.61 alpha:1].CGColor;
//Draw a rectangle
CGContextSetFillColorWithColor(context, myColor);
//Define a rectangle
CGContextAddRect(context, CGRectMake(0, 0, 95.0, 110.0));
//Draw it
CGContextFillPath(context);

}

then, I have a separate UIViewController that has a UISlider in it

-(IBAction) sliderChanged:(id) sender{

UISlider *slider = (UISlider *)sender;
int sliderValue = (int)[slider value];
float sliderFloat = (float) sliderValue;

NSLog(@"sliderValue ... %d",sliderValue);
NSLog(@"sliderFloat ... %.1f",sliderFloat / 100);

}

here, in sliderChanged, I would like to be able to dynamically change the background color of the rectangle being drawn in the UIView subclass. how should i go about implementing this ?

thank you!

Answer 1

Create a property of your UIView-Subclass which holds a UIColor (or CGColor) value:

In the header:

@interface MySub : UIView {
NSColor* rectColor;
}

@property (retain) NSColor* rectColor;
@end

In the implementation file:

@implementation MySub
@synthesize rectColor
@end

You can now set the color with myViewInstance.rectColor = SomeNSColor;

After you've set the color, you have to redraw the view in order to draw the rect with the new background color:

[myViewInstance setNeedsDisplay];