iOS/iPhone Set Image Alpha/Opacity with Slider (UIImageView and UISlider)

[imgView setAlpha:0.5];

//
//  ViewController.h
//  imageViewSliderAlpha
//
//  Created by Weerachai on 12/5/55 BE.
//  Copyright (c) 2555 Weerachai. All rights reserved.
//

#import <UIKit/UIKit.h>

@interface ViewController : UIViewController
{
    IBOutlet UIImageView *imgView;
    IBOutlet UISlider *sliderObj;
}

- (IBAction)sliderChanged:(id)sender;

@end

//
//  ViewController.m
//  imageViewSliderAlpha
//
//  Created by Weerachai on 12/5/55 BE.
//  Copyright (c) 2555 Weerachai. All rights reserved.
//

#import "ViewController.h"

@interface ViewController ()

@end

@implementation ViewController

- (void)viewDidLoad
{
    [super viewDidLoad];
	// Do any additional setup after loading the view, typically from a nib.
    
    UIImage* img = [UIImage imageNamed:@"girl.jpg"];
    [imgView setImage:img];
}

- (IBAction)sliderChanged:(id)sender {
    float value = [sliderObj value];
	[imgView setAlpha:value];
}

- (void)didReceiveMemoryWarning
{
    [super didReceiveMemoryWarning];
    // Dispose of any resources that can be recreated.
}

- (void)dealloc {
    [imgView release];
    [sliderObj release];
    [super dealloc];
}

@end