Basic example for how to change a visible object's shadow path

C4WorkSpace.m

//
//  C4WorkSpace.m
//
//  Created by Travis Kirton.
//
 
#import "C4WorkSpace.h"
 
@implementation C4WorkSpace {
    C4Shape *s, *c;
    BOOL circleShadow;
}
 
-(void)setup {
    c = [C4Shape ellipse:CGRectMake(0, 0, 100, 100)];
    s = [C4Shape rect:c.frame];
    s.center = self.canvas.center;
    [self.canvas addShape:s];
    [self runMethod:@"newShadowPath" afterDelay:0.05f];
    [self runMethod:@"showPath" afterDelay:0.1f];
}
 
-(void)newShadowPath {
    if(circleShadow) {
        s.shadowPath = c.shapeLayer.path;
        circleShadow = NO;
    }
    else {
        s.shadowPath = s.shapeLayer.path;
        circleShadow = YES;
    }
}
 
-(void)showPath {
    s.animationDuration = 1.0f;
    s.shadowOffset = CGSizeMake(20,20);
    s.shadowOpacity = 0.8;
}
 
-(void)touchesBegan {
    [self newShadowPath];
}
 
@end