UIImageView+JMImageCache.m

//
//  UIImageView+JMImageCache.m
//  JMImageCacheDemo
//
//  Created by Jake Marsh on 7/23/12.
//  Copyright (c) 2012 Jake Marsh. All rights reserved.
//

#import "UIImageView+JMImageCache.h"
#import "JMImageCache.h"
#import <objc/runtime.h>

static char kJMImageURLObjectKey;

@interface UIImageView (_JMImageCache)

@property (readwrite, nonatomic, retain, setter = jm_setImageURL:) NSURL *jm_imageURL;

@end

@implementation UIImageView (_JMImageCache)

@dynamic jm_imageURL;

@end

@implementation UIImageView (JMImageCache)

#pragma mark - Private Setters

- (NSURL *) jm_imageURL {
    return (NSURL *)objc_getAssociatedObject(self, &kJMImageURLObjectKey);
}

- (void) jm_setImageURL:(NSURL *)imageURL {
    objc_setAssociatedObject(self, &kJMImageURLObjectKey, imageURL, OBJC_ASSOCIATION_RETAIN_NONATOMIC);
}

#pragma mark - Public Methods

- (void) setImageWithURL:(NSURL *)url {
    [self setImageWithURL:url placeholder:nil];
}

- (void) setImageWithURL:(NSURL *)url placeholder:(UIImage *)placeholderImage {
    [self setImageWithURL:url key:nil placeholder:placeholderImage];
}

- (void) setImageWithURL:(NSURL *)url placeholder:(UIImage *)placeholderImage completion:(void (^)(UIImage *))completion {
    [self setImageWithURL:url key:nil placeholder:placeholderImage completion:completion];
}

- (void) setImageWithURL:(NSURL *)url key:(NSString*)key placeholder:(UIImage *)placeholderImage {
    [self setImageWithURL:url key:key placeholder:placeholderImage completion:nil];
}

- (void)setImageWithURL:(NSURL *)url key:(NSString*)key placeholder:(UIImage *)placeholderImage completion:(void (^)(UIImage *image))completion {
    self.jm_imageURL = url;
    
    // If the imageView didn't had an image, we set the placeholder image
    if (!self.image && placeholderImage) {
        self.image = placeholderImage;
        [self setNeedsDisplay];
        [self setNeedsLayout];
    }
    
    // Completion block executed after the fetch
    __weak UIImageView *safeSelf = self;
    void (^imageCompletionBlock)(UIImage *) = ^(UIImage *image) {
        if(image) {
            safeSelf.image = image;
            [safeSelf setNeedsLayout];
            [safeSelf setNeedsDisplay];
        }
        safeSelf.jm_imageURL = nil;
        if (completion) completion(image);
    };
    
    // Get image from cache (execute in background if using disk or network)
    if (key) {
        [[JMImageCache sharedCache] imageForURL:url key:key completionBlock:imageCompletionBlock];
    } else {
        [[JMImageCache sharedCache] imageForURL:url completionBlock:imageCompletionBlock];
    }
}

@end