To create marquee effect first set scroll view either via storyboard or via code
Here in this example I am setting up scroll view via code.

declare these variables

•     UIScrollView *scrollView;
•     NSTimer *timer;
•     CGFloat contentOffset;

1. Set up scroll view.

-(void)configureScrollView //call this function when you need to set scrollView
{
    float width = self.view.bounds.size.width;
    scrollView = [[UIScrollView alloc]initWithFrame:CGRectMake(0, 0, width, 162)];
    scrollView.delegate = self;
    scrollView.backgroundColor = [UIColor whiteColor];
    [self.view addSubview:scrollView];
    scrollView.contentSize = CGSizeMake(width*self.imageArray.count,0);
    scrollView.pagingEnabled = YES;
    scrollView.showsHorizontalScrollIndicator = YES;
    [self setupScrollView:scrollView];
}

2.

- (void)setupScrollView:(UIScrollView*)scrMain {
   [self addImageArrayToScrollView:scrMain image:self.imageArray ];//send image array to this function.
    // enable timer after each 2 seconds for scrolling.
    [NSTimer scheduledTimerWithTimeInterval:2 target:self selector:@selector(scrollingTimer) userInfo:nil repeats:YES];
}

3. This function will set the image array  to index according to array count.

-(void)addImageArrayToScrollView:(UIScrollView*)scrlView image:(NSArray*)imgarr {
    for(int index=0; index < [self.imageArray count]; index++)
    {
        NSDictionary *dict=[self.imageArray objectAtIndex:index];
        NSString *image=[dict valueForKey:@"image_slide"];
        UIImageView *bigImage=[[UIImageView alloc]init];
        bigImage.frame = CGRectMake(scrlView.bounds.size.width*index, 0, self.view.bounds.size.width, 162);
        [bigImage setImageWithURL:[NSURL URLWithString:[image stringByAddingPercentEncodingWithAllowedCharacters:[NSCharacterSet URLQueryAllowedCharacterSet]]]];
        [self.objectArray insertObject:bigImage atIndex:index];
        [scrlView addSubview:bigImage];
        [scrlView addSubview:[self.objectArray objectAtIndex:index]];
    }
}

4. To change the image after each 2 seconds

- (void)scrollingTimer {
    // calculate next page to display
    int nextPage = (int)(contentOffset/scrollView.frame.size.width) + 1 ;
    // if page is not equals to the array count, display it
    if( nextPage <= self.imageArray.count )  {
        [scrollView setContentOffset:CGPointMake(contentOffset, 0) animated:YES];
        contentOffset = contentOffset + self.view.bounds.size.width;
        // else start sliding form 1
    } else {
        contentOffset = 0;
        [scrollView setContentOffset:CGPointMake(contentOffset, 0) animated:YES];
    }
}

5. Don’t forget to set contentOffSet in viewDidLoad
 

  - (void)viewDidLoad {
    [super viewDidLoad];
    contentOffset = 0;
    // Do any additional setup after loading the view.
}