Download an image with ProgressBar in iOS

Hi all,

Today I will show you how you can download an image showing complete progress.

Make sure that you have an interface like the below image.

You should link all the interface views with the corresponding variables in ViewController.h

ViewController.h

#import <uikit /UIKit.h>

@interface ViewController : UIViewController <nsurlconnectiondatadelegate>

@property (weak, nonatomic) IBOutlet UIProgressView *progressView;
@property (weak, nonatomic) IBOutlet UIImageView *imageView;
@property (nonatomic, weak) IBOutlet UIButton   *btn_download;
@property (nonatomic, weak) IBOutlet UILabel   *lbl_download;

@end

ViewController.m

#import "ViewController.h"

@interface ViewController ()

@property (strong, nonatomic) NSURLConnection *connectionManager;
@property (strong, nonatomic) NSMutableData *downloadedMutableData;
@property (strong, nonatomic) NSURLResponse *urlResponse;

@end

@implementation ViewController{
    
#define IMAGE_URL @"http://img1.wikia.nocookie.net/__cb20111229061816/lego/images/b/b8/Ws-space-apple-logo.jpg"
}

- (void)viewDidLoad
{
    [super viewDidLoad];   
}

-(IBAction)downloadImage :(id)sender{
    
    self.btn_download.enabled = NO;
    self.downloadedMutableData = [[NSMutableData alloc] init];
    NSURLRequest *urlRequest = [NSURLRequest requestWithURL:[NSURL URLWithString:IMAGE_URL]
                                                cachePolicy:NSURLRequestReloadIgnoringLocalCacheData
                                            timeoutInterval:60.0];
    self.connectionManager = [[NSURLConnection alloc] initWithRequest:urlRequest delegate:self];
    
}

- (void)didReceiveMemoryWarning
{
    [super didReceiveMemoryWarning];
}

#pragma mark - Delegate Methods
-(void)connection:(NSURLConnection *)connection didReceiveResponse:(NSURLResponse *)response {
    NSLog(@"%lld", response.expectedContentLength);
    self.urlResponse = response;
}

-(void)connection:(NSURLConnection *)connection didReceiveData:(NSData *)data {
    [self.downloadedMutableData appendData:data];
    self.progressView.progress = ((100.0/self.urlResponse.expectedContentLength)*self.downloadedMutableData.length)/100;
    
    float per = ((100.0/self.urlResponse.expectedContentLength)*self.downloadedMutableData.length);
    self.lbl_download.text = [NSString stringWithFormat:@"%0.f%%", per];
    
    if (self.progressView.progress == 1) {
        self.progressView.hidden = YES;
        self.btn_download.enabled = YES;
    } else {
        self.progressView.hidden = NO;
    }
    
}

-(void)connectionDidFinishLoading:(NSURLConnection *)connection {
    self.imageView.image = [UIImage imageWithData:self.downloadedMutableData];
    self.lbl_download.text = @"Download Complete";
}

@end

You can download the complete source code from here.