Make image appear after button push - iphone

Question

I am trying to change the background color and make an image appear on the screen when a button is pushed. I can get the color to change, but I can't get a trace of the image to appear. I don't know how to place the image on the screen either. I am using iOS 5 and storyboard, but I have not added the UIImageView to the storyboard, as I want it to appear.
My ViewController.h
#import <UIKit/UIKit.h>
#interface ViewController : UIViewController
- (IBAction)changeButton:(id)sender;
#end
My ViewController.m
#import "ViewController.h"
#interface ViewController ()
#end
#implementation ViewController
- (void)viewDidLoad
{
[super viewDidLoad];
// Do any additional setup after loading the view, typically from a nib.
}
- (void)didReceiveMemoryWarning
{
[super didReceiveMemoryWarning];
// Dispose of any resources that can be recreated.
}
-(void)colorchange
{
self.view.backgroundColor = [UIColor greenColor];
}
-(void)imageShow
{
UIImage *image = [UIImage imageNamed:#"logo-tag-centered.pmg"];
UIImageView *imgView = [[UIImageView alloc] initWithFrame:CGRectMake(0, 0, 0, 0)];
[imgView setImage:image];
}
- (IBAction)changeButton:(id)sender
{
[self colorchange];
[self imageShow];
}
#end
Any help would be greatly appreciated! Thanks!

Answer 1

You have to add the image view to your view controller's view.
- (void)showImage
{
UIImage *image = [UIImage imageNamed:#"logo-tag-centered.png"];
UIImageView *imgView = [[UIImageView alloc] initWithImage:image];
imgView.center = CGPointMake(self.view.bounds.size.width / 2.0f, self.view.bounds.size.height / 2.0f);
[self.view addSubview:imgView];
}

Answer 2

You haven't added the image view anywhere to the main view. You could do this:
- (void)viewDidLoad
{
[super viewDidLoad];
UIImage *image = [UIImage imageNamed:#"logo-tag-centered.pmg"];
UIImageView *imgView = [[UIImageView alloc] initWithFrame:CGRectMake(0, 0, 0, 0)];
[imgView setImage:image];
[imgView setHidden:YES];
[self.view addSubview:imgView];
}
-(void)imageShow
{
[imgView setHidden:NO];
}
- (IBAction)changeButton:(id)sender
{
[self colorchange];
[self imageShow];
}