The canvas listening for all touches from all objects.

C4WorkSpace.m

//
//  C4WorkSpace.m
//  Notification Tutorial
//
//  Created by Travis Kirton.
//

#import "C4WorkSpace.h"

@implementation C4WorkSpace

-(void)setup {
    [self listenFor:@"touchesBegan" andRunMethod:@"react"];
    
    C4Shape *s = [C4Shape ellipse:CGRectMake(0, 0, 192, 192)];
    s.center = self.canvas.center;
    [self.canvas addShape:s];
}

-(void)react {
    self.canvas.backgroundColor = [UIColor colorWithWhite:[C4Math randomInt:100]/100.0f alpha:1.0f];
}

@end