Put an image on the screen and then allow for a user to drag by way of a touch event. This example comes from the book "iOS Programming: The Big Nerd Ranch Guide, Third Edition" by Joe Conway and Aaron Hillegas.

gistfile1.m

#import "PMViewController.h"
#import <QuartzCore/QuartzCore.h>

@interface PMViewController ()
{
    CALayer *boxLayer;
}
@end

@implementation PMViewController

- (void)viewDidLoad
{
    [super viewDidLoad];
  // Do any additional setup after loading the view, typically from a nib.
    self.view.backgroundColor = [UIColor whiteColor];
    
    boxLayer = [[CALayer alloc] init];
    boxLayer.bounds = CGRectMake(0.0,0.0,85.0,85.0);
    boxLayer.position = CGPointMake(160.0, 100.0);
    
    UIImage *layerImage = [UIImage imageNamed:@"Hypno.png"];
    
    CGImageRef image = [layerImage CGImage];
    
    boxLayer.contents = (__bridge id)image;
    
    boxLayer.contentsRect = CGRectMake(-0.1, -0.1, 1.2, 1.2);
    
    boxLayer.contentsGravity = kCAGravityResizeAspect;
    
    [self.view.layer addSublayer:boxLayer];
}

-(void)touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event
{
    UITouch *t = [touches anyObject];
    CGPoint p = [t locationInView:self.view];
    boxLayer.position = p;
}

-(void)touchesMoved:(NSSet *)touches withEvent:(UIEvent *)event
{
    UITouch *t = [touches anyObject];
    CGPoint p = [t locationInView:self.view];
    [CATransaction begin];
    [CATransaction setDisableActions:YES];
    boxLayer.position = p;
    [CATransaction commit];
}

@end