Does anyone have ideas about how to implement the scrolling effect as in the 'Applauz

Discussion in 'iOS Programming' started by narmada m, May 30, 2013.

  1. narmada m macrumors newbie

    Joined:
    May 30, 2013
    #1
    Does anyone have ideas about how to implement the scrolling effect as in the 'Applauze' iPhone app in iOS? How to implement this event screen - scrolling effect with the images gradually expanding on scroll up and contract on scroll down in ios. Plz, check this link: itunes.apple.com/us/app/applauze/id608609424?mt=8 (first screenshot)
     
  2. MattInOz macrumors 68030

    MattInOz

    Joined:
    Jan 19, 2006
    Location:
    Sydney
    #2
    At a guess I'd say they are using scroll offset to alter the image scale value. Maybe?
     
  3. Duncan C macrumors 6502a

    Duncan C

    Joined:
    Jan 21, 2008
    Location:
    Northern Virginia
    #3
    Animation effects like you describe are pretty easy to do using UIView animation. Take a look at the UIView class methods who's names start with animateWithDuration:

    For more complex animation you can create CAAnimation objects and add them to the layers of the views you want to animate.

    I created a scrolling credits screen for our latest app, Face Dancer. It animates the credits in pages, where each page scrolls up quickly until it's near the center of the screen, then slows to a crawl for several second, then animates away at the same time the next page is animating into place.

    Making the images expand in size as they scroll would just mean adding another couple of lines to the animation code. (Creating a CGAffineTransform for the view that scales it smaller, and animating the transform back to full size as it moves onto the screen, then animating the transform back to a smaller size as it scrolls offscreen again.

    BTW, I've never seen the "Applauz" app. Can you either describe the effect in detail or post a video clip of the animation you're after?
     
  4. Duncan C macrumors 6502a

    Duncan C

    Joined:
    Jan 21, 2008
    Location:
    Northern Virginia
    #4

    I just downloaded the app and tried it out. It looks like the frame of the images expand as you scroll, but the images themselves do not grow.

    Given that the app requires iOS 6, I would bet that they are using collection views and auto-layout. Collection views are a lot like table views, but offer many more options. Auto-layout gives you more flexible control of the size of your view components. I've dabbled with both, but am not an expert on either (our company is currently targeting iOS 5, so we haven't focused on iOS6 only APIs yet. We are considering the move to iOS6 based apps, but have not decided to develop iOS6 only apps yet.)
     

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