SwiftImageViewer

Easily customizable scaling Image Viewer & View Controller written by Swift.

I am not sure whether this library is useful or not.

Platform: XCode 8.0 beta 3, Swift3.0

Purpose of this library is to write customized image view controllers easily. Zooming and scrolling functionality is shared and you can display local image, image from network and animated gif images as well.

Quick Guide

• In a word, you use this generic class to display image.

  public class SIVImageViewController<ImageView:SIVImageViewType, LoadingView:SIVImageLoadingIndicatorViewType where ImageView:UIView, LoadingView:UIView>: UIViewController

• SIVDefaultImageViewController which uses UIImageView and SIVDefaultImageLoadingView

  public typealias SIVDefaultImageViewController = SIVImageViewController<UIImageView, SIVDefaultImageLoadingView>

Set source property of image view controller's property to display image.

Assign barVisibiltyHandler closure property to receive visibilty request (Bars toggle with single tap on image or hide on image zooming). The signal is already throttled within 0.4 second interval and you can set bar's visibilty in this closure.

Please check example project.

Features

• Make it possible to display not only static image but other type of image like animated gif

  public enum SIVImage{
     case image(UIImage)
     case data(Data, CGSize)
     
     // Image Size
     internal var size:CGSize {
       switch self {
       case let image(img):
           return img.size
       case let data(_, sz):
           return sz
       }
     }
     
     // Can make it public
     internal func toUIImage() -> UIImage?{
       switch self {
       case let image(img):
           return img
       case let data(dt, _):
           return UIImage(data: dt)
       }
     }
  }

• Can easily integrate any image resources with a few lines of code. Images can be loaded using SDWebImage, KingFisher or some other libraries. Displaying these kinds of images is not so difficult.

  /// Image Load Result with success & failed
  public enum SIVImageLoadResult{
      case success(SIVImage)
      case failed(ErrorProtocol?)
  }
  
  public protocol SIVImageSourceType {
      /// Cached Image, so before loading, check this property and display directly.
      var loadedImage:SIVImage? { get }
      
      /// Preview Image of image
      var previewImage:SIVImage? { get }   // Ability to support preview image
   
      /// Load function
      func load(progress:((Double) -> ())?, completion:((SIVImageLoadResult) -> ()))
   }

  You only need to write some kind of Wrapper Type that conforms SIVImageSourceType.

  A simple UIImage wrapper type is like this

  // MARK: Immediate Image Source
  struct ImmediateImageSource{
     var image:UIImage
  }
  
  extension ImmediateImageSource: SIVImageSourceType {
     var loadedImage:SIVImage?{
       return .image(image)
     }
     var previewImage:SIVImage?{
       return nil
     }
   
     func load(progress: ((Double) -> ())?, completion: ((SIVImageLoadResult) -> ())) {
       progress?(1.0)
       completion(.success(.image(image)))
     }
  }

  Check DelayedImageSource struct in example project to get idea about this.

• Can use other view type than UIImageView to display image (e.g. FLAnimatedImageView )

  public protocol SIVImageViewType: class {
    var sivImage:SIVImage? { get set }
  }

  • UIImageView example

    This is already done in this library

  // MARK: - Conform to SIVImageViewType
  extension UIImageView:SIVImageViewType {
    public var sivImage:SIVImage? {
      get {
        return image.flatMap{.image($0)}
      }
      set {
        image = newValue?.toUIImage()
      }
    }
  }

  Try your self to make `FLAnimatedImageView` to conform `SIVImageViewType`. :smile:
  
  You can even use other type of view which can display image or animated image.
  

• Easily integrate customized loading indicator

  public protocol SIVImageLoadingIndicatorViewType: class {
     /// Set this property to update loading indicator view's progress.
     var progress:Double { get set }
   
     /// Loading Indicator view might have reload button, handler for it.
     var reloadHandler:SIVClosure? { get set }
   
     /// If Loading Indicator supports single tap for updating visibilty of control bar, implementing class can call this method
     var singleTapHandler:SIVClosure? { get set }
   
     /**
     Update with result, in case of success, this view will be removed from its superview so before doing it, there might be some animation
     */
     func update(withResult result:SIVImageLoadResult, completion:SIVClosure?)
   
     // Layout Size for this indicator view type
     static var layoutSize:SIVImageLoadingIndicatorViewSize { get }
  

}

public enum SIVImageLoadingIndicatorViewSize{ case fullScreen // This indicator fills whole screen case centered(CGSize) // Indicator is centered with specific size.

var autoresizingMask:UIViewAutoresizing {
    switch self {
    case .fullScreen:
        return [.flexibleWidth, .flexibleHeight]
    case .centered(_):
        return [.flexibleLeftMargin, .flexibleRightMargin, .flexibleTopMargin, .flexibleBottomMargin]
    }
}

}

Check `SIVDefaultImageLoadingView` class to get idea about how to write customized loading indicator.


### TODO List

- `FLAnimatedImageView` extension to conform `SIVImageViewType`
- `KingFisher` and `SDWebImage` wrapper `SIVImageSourceType`s
- Example using `UIPageViewController` to browse images.
- Example using `UICollectionViewController` and `UIPageViewController` to show custom transitions for photo browsing.



### License

- [MRProgress](https://github.com/mrackwitz/MRProgress)
  
  Library is using `MRProgress` library to implement `SIVDefaultImageLoadingView`
  
- MIT