orta / fastimagecacheexample

The simplest possible use of FastImageCache

FastImageCacheExample

The simplest possible use of FastImageCache: Throwing a single bundled image on the screen.

I didn't write FastImageCache.

Overall

Setup the FICImageCache somewhere, an easy place to start it App Delegate

    // Configure the image cache
    FICImageCache *sharedImageCache = [FICImageCache sharedImageCache];
    [sharedImageCache setDelegate:self];

    // Reuse the Path image formats
    FICImageFormatDevices squareImageFormatDevices = FICImageFormatDevicePhone | FICImageFormatDevicePad;
    FICImageFormat *squareImageFormat16BitBGR = [FICImageFormat formatWithName:FICDPhotoSquareImage16BitBGRFormatName family:FICDPhotoImageFormatFamily
                                                                     imageSize:FICDPhotoSquareImageSize style:FICImageFormatStyle16BitBGR
                                                                  maximumCount:250 devices:squareImageFormatDevices protectionMode:FICImageFormatProtectionModeNone];
    
    [sharedImageCache setFormats:@[squareImageFormat16BitBGR]];

Wherever this class is it needs to do the work of connecting an to a UIImage.

- (void)imageCache:(FICImageCache *)imageCache wantsSourceImageForEntity:(id<FICEntity>)entity withFormatName:(NSString *)formatName completionBlock:(FICImageRequestCompletionBlock)completionBlock {
    dispatch_async(dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0), ^{

        NSURL *filePathURL = [entity sourceImageURLWithFormatName:formatName];        
        UIImage *sourceImage = [UIImage imageWithData:[NSData dataWithContentsOfURL:filePathURL]];
        
        dispatch_async(dispatch_get_main_queue(), ^{
            completionBlock(sourceImage);
        });
    });
}

You have to include the other methods, these will probably come in useful later:

- (BOOL)imageCache:(FICImageCache *)imageCache shouldProcessAllFormatsInFamily:(NSString *)formatFamily forEntity:(id<FICEntity>)entity {
    return NO;
}

- (void)imageCache:(FICImageCache *)imageCache errorDidOccurWithMessage:(NSString *)errorMessage {
    NSLog(@"%@", errorMessage);
}

You now need an object that conforms to the <FICEntity> protocol. Here's a gotcha for me. The UUIDs have to go through FICUUIDBytesFromMD5HashOfString & FICStringWithUUIDBytes before they get matched correctly, if they don't it will silently not find your image. I initially used a string here. Read their readme for more info.

@interface ORImage : NSObject <FICEntity>

@property (nonatomic, copy) NSString *filename;

@end

You can't skip drawingBlockForImage:withFormatName: even if you're just redrawing the image.

@implementation ORImage {
    NSString *_UUID;
}

- (NSString *)UUID
{
    if (_UUID == nil) {
        CFUUIDBytes UUIDBytes = FICUUIDBytesFromMD5HashOfString(self.filename);
        _UUID = FICStringWithUUIDBytes(UUIDBytes);
    }
    return _UUID;

}

- (NSString *)sourceImageUUID
{
    return self.UUID;
}

- (NSURL *)sourceImageURLWithFormatName:(NSString *)formatName 
{
    return [[NSBundle mainBundle] URLForResource:self.filename withExtension:@"jpg"];
}

- (FICEntityImageDrawingBlock)drawingBlockForImage:(UIImage *)image withFormatName:(NSString *)formatName 
{
    FICEntityImageDrawingBlock drawingBlock = ^(CGContextRef context, CGSize contextSize) {
        CGRect contextBounds = CGRectZero;
        contextBounds.size = contextSize;
        CGContextClearRect(context, contextBounds);
        
        UIGraphicsPushContext(context);
        [image drawInRect:contextBounds];
        UIGraphicsPopContext();
    };
    
    return drawingBlock;
}

Next you need to make sure you have your image table formats set up correctly, I reused more of Paths:

NSString *const FICDPhotoImageFormatFamily = @"FICDPhotoImageFormatFamily";
NSString *const FICDPhotoSquareImage16BitBGRFormatName = @"com.path.FastImageCacheDemo.FICDPhotoSquareImage16BitBGRFormatName";
CGSize const FICDPhotoSquareImageSize = {240, 240};

and

extern NSString *const FICDPhotoSquareImage16BitBGRFormatName;
extern NSString *const FICDPhotoImageFormatFamily;

With all this set up you're now ready to call something like this to get an image from the cache:

self.image = [[ORImage alloc] init];
self.image.filename = @"pizza";

[[FICImageCache sharedImageCache] retrieveImageForEntity:self.image withFormatName:FICDPhotoSquareImage16BitBGRFormatName completionBlock:^(id<FICEntity> entity, NSString *formatName, UIImage *image) {
    [self.imageView setImage:image];
}];

And you've got the first image going through the FIC pipeline, now you build from there.