objc_setAssociatedObject , objc_getAssociatedObject

#import <objc/runtime.h>

예제1)

// set

    {

        objc_setAssociatedObject(self, @"ShouldDismissModalViewLater", modalViewController, OBJC_ASSOCIATION_ASSIGN);

    }

    

    // get and using

    {

        UIViewController *modalVC = objc_getAssociatedObject(self, @"ShouldDismissModalViewLater");

        [modalVC dismissViewControllerAnimated:YES completion:nil];

    }

예제2)

// set

    {

        NSArray *gotArray;

        objc_setAssociatedObject(self, @"MyGotArray", gotArray, OBJC_ASSOCIATION_RETAIN_NONATOMIC);

    }

    

    // get and using

    {

        NSArray *array = objc_getAssociatedObject(self, @"MyGotArray");

        [array enumerateObjectsUsingBlock:^(id obj, NSUInteger idx, BOOL *stop) {

            

        }];

    }

예제3)

Easier syntax

Alternatively you could use @selector(nameOfGetter) instead of creating a static pointer. Why? See http://stackoverflow.com/a/16020927/202451. Example:

- (NSArray *)laserUnicorns {
    return objc_getAssociatedObject(self, @selector(laserUnicorns));
}

- (void)setLaserUnicorns:(NSArray *)unicorns {
    objc_setAssociatedObject(self, @selector(laserUnicorns), unicorns, OBJC_ASSOCIATION_RETAIN_NONATOMIC); 
}




async download images

NSURLSession를 이용한 방법)

xxx.h

NSURLSession *mealNewsUrlSession;

xxx.m

// initialization

mealNewsUrlSession = [NSURLSession sessionWithConfiguration:[NSURLSessionConfiguration defaultSessionConfiguration]];

// use

NSURL *imageURL = [NSURL URLWithString:imagePath];

            NSURLRequest *request = [NSURLRequest requestWithURL:imageURL];

            NSURLSessionDataTask *task = [mealNewsUrlSession dataTaskWithRequest:request completionHandler:^(NSData *data, NSURLResponse *response, NSError *error) {

                if (error)

                {

                    NSLog(@"ERROR: %@", error);

                }

                else

                {

                    NSHTTPURLResponse *httpResponse = (NSHTTPURLResponse *)response;

                    

                    if (httpResponse.statusCode == 200)

                    {

                        UIImage *image = [UIImage imageWithData:data];

                        [mealNewsImageCache setObject:image forKey:imagePath];

                        

                        dispatch_async(dispatch_get_main_queue(), ^{

                            [cell.mealPhoto setImage:image];

                            [cell setNeedsLayout];

                            //[cell.activityIndicator stopAnimating];

                        });

                    }

                    else

                    {

                        NSLog(@"Couldn't load image at URL: %@", imageURL);

                        NSLog(@"HTTP %ld", (long)httpResponse.statusCode);

                    }

                }

            }];

            [task resume];

dispatch를 이용한 방법)

dispatch_queue_t queue = dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_HIGH, 0);

        dispatch_async(queue, ^(void) {

            

            NSData *imageData = [NSData dataWithContentsOfURL:[NSURL URLWithString:profilePath]];

            UIImage* image = [[UIImage alloc] initWithData:imageData];

            if (image) {

                [mealNewsImageCache setObject:image forKey:profilePath];

                

                dispatch_async(dispatch_get_main_queue(), ^{

                    [self.profilePhoto setImage:image forState:UIControlStateNormal];

                });

            }

        });

3. 한번에 모두 다운로드 한후에 이용하는 방법)

xxx.h

NSOperationQueue *_asyncQueue;

xxx.m

// initialization

{

_asyncQueue = [[NSOperationQueue alloc] init];

or

_asyncQueue = [NSOperationQueue mainQueue]

or

_asyncQueue = [NSOperationQueue currentQueue]

}

{

// use

dispatch_async(dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0), ^{

        NSURLRequest *request = [NSURLRequest requestWithURL:url];

        [NSURLConnection sendAsynchronousRequest:request queue:_asyncQueue completionHandler:^(NSURLResponse *response, NSData *data, NSError *connectionError) {

            

            UIImage *image = [[UIImage alloc] initWithData:data];

            [Utility saveImageToFS:UIImageJPEGRepresentation(image, 1.0) withUrl:request.URL];

            

            dispatch_async(dispatch_get_main_queue(), ^{

                //update cell

            });

        }];

    }); //dispatch_async

}

+ (void) saveImageToFS:(NSData *)data withUrl:(NSURL *)url {

    NSString *dir = [[url absoluteString] stringByDeletingLastPathComponent];

    NSString *filename = [url.absoluteString lastPathComponent];

    

    //

    NSString *path = [NSString stringWithFormat:@"%@/%@",[Utility getMangaRootPath],dir];

    if(![[NSFileManager defaultManager] createDirectoryAtPath:path withIntermediateDirectories:YES attributes:nil error:nil])

        NSLog(@"fail to create directory ");

    

    

    NSString *fullpath = [path stringByAppendingFormat:@"/%@",filename];

    if(![data writeToFile:fullpath atomically:YES])

        NSLog(@"fail to write file");

}

+ (NSString *)getMangaRootPath {

    NSString *path = [NSString stringWithFormat:@"%@/%@",

                      [self getCachesPath],

                      kMangaEditionDirectory];

    // create directory

    [[NSFileManager defaultManager] createDirectoryAtPath:path withIntermediateDirectories:YES attributes:nil error:nil];

    return path;

}

+ (NSString*)getCachesPath {

    NSString *documentPath = nil;

    

    NSSearchPathDirectory directory;

    directory = NSCachesDirectory;

    

    NSArray* directories = NSSearchPathForDirectoriesInDomains(directory, NSUserDomainMask, YES);

if(directories != nil && [directories count] > 0)

        documentPath = [directories objectAtIndex:0];

    return documentPath;

}