AirDropSample/APLAsyncImageActivityItemProvider.m

/*
 
     File: APLAsyncImageActivityItemProvider.m
 Abstract: Subclass of UIActivityItemProvider that downloads a file asynchronously after the user has chosen their sharing option.
  Version: 1.0
 
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 */
 
#import "APLAsyncImageActivityItemProvider.h"
#import "UIImage+Resize.h"
 
@interface APLAsyncImageActivityItemProvider()
 
@property (strong, atomic) UIImage *image; //Use atomic to make sure access is synchronized.
 
@end
 
@implementation APLAsyncImageActivityItemProvider
 
 
- (id)activityViewControllerPlaceholderItem:(UIActivityViewController *)activityViewController
{
    return [[UIImage alloc] init];
}
 
/****************************************************
 item
 
 The item method runs on a secondary thread using an NSOperationQueue (UIActivityItemProvider subclasses NSOperation).
 The implementation of this method loads an image from the app's bundle and applies two filters to it.
 
 ******************************************************/
- (id)item
{
    //Notify the delegate on the main thread that the processing is beginning.
    dispatch_async(dispatch_get_main_queue(), ^{
        [self.delegate imageActivityItemProviderPreprocessingDidBegin:self];
    });
    
    //Load image.
    UIImage *image = [UIImage imageNamed:@"Flower.png"];
    
    //Start progress.
    dispatch_async(dispatch_get_main_queue(), ^{
        [self.delegate imageActivityItemProvider:self preprocessingProgressDidUpdate:0.2];
    });
    
    //Create Core Image context.
    CIContext *context = [CIContext contextWithOptions:nil];
    
    //Scale image for context.
    CGFloat scale = [[UIScreen mainScreen] scale];
    CGSize imageSize = CGSizeMake([context inputImageMaximumSize].width/scale/1.5, [context inputImageMaximumSize].height/scale/1.5);
    image = [UIImage imageWithImage:image scaledToFitToSize:imageSize];
    
    //Update progress after scaling.
    dispatch_async(dispatch_get_main_queue(), ^{
        [self.delegate imageActivityItemProvider:self preprocessingProgressDidUpdate:0.5];
    });
    
    
    //Add sepia filter.
    CIImage *sepiaImage = [CIImage imageWithCGImage:[image CGImage]];
    CIFilter *filter = [CIFilter filterWithName:@"CISepiaTone"];
    [filter setValue:sepiaImage forKey:kCIInputImageKey];
    CIImage *sepiaResult = [filter valueForKey:kCIOutputImageKey];
    
    //First filter complete.
    dispatch_async(dispatch_get_main_queue(), ^{
        [self.delegate imageActivityItemProvider:self preprocessingProgressDidUpdate:0.7];
    });
    
    //Add gloom filter.
    CIFilter *gloom = [CIFilter filterWithName:@"CIGloom"];
    [gloom setValue:sepiaResult forKey:kCIInputImageKey];
    [gloom setValue: [NSNumber numberWithFloat: 1.75] forKey: @"inputIntensity"];
    CIImage *gloomResult = [gloom valueForKey:kCIOutputImageKey];
    
    //Second filter complete.
    dispatch_async(dispatch_get_main_queue(), ^{
        [self.delegate imageActivityItemProvider:self preprocessingProgressDidUpdate:0.9];
    });
    
    //Create CGImage with filters applied.
    CGImageRef cgImage = [context createCGImage:gloomResult fromRect:[gloomResult extent]];
    
    //Progress completed.
    dispatch_async(dispatch_get_main_queue(), ^{
        [self.delegate imageActivityItemProvider:self preprocessingProgressDidUpdate:1.0];
    });
    
    //Notify the delegate on the main thread that the processing has finished.
    dispatch_async(dispatch_get_main_queue(), ^{
        [self.delegate imageActivityItemProviderPreprocessingDidEnd:self];
    });
    
    UIImage *newImage = [UIImage imageWithCGImage:cgImage];
    CFRelease(cgImage);
    
    self.image = newImage;
    return newImage;
 
}
 
- (UIImage *)activityViewController:(UIActivityViewController *)activityViewController thumbnailImageForActivityType:(NSString *)activityType suggestedSize:(CGSize)size
{
    //The filtered image is the image to display on the other side.
    return [UIImage imageWithImage:self.image scaledToFillToSize:size];
}
 
@end