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Download a file / image with AFNetworking in iOS?

I thought I had it figured out but I just can't get it to work. I have a method that is called on every URL in an array. This method have a URL of a picture that should be downloaded in specific path in a Application Support folder for offline use. But maybe I'm misinterpreting the methods in the AFNetwork library. My method looks like this:

- (void) downloadImageInBackground:(NSDictionary *)args{

  @autoreleasepool {

    NSString *photourl = [args objectForKey:@"photoUrl"];
    NSString *articleID = [args objectForKey:@"articleID"];
    NSString *guideName = [args objectForKey:@"guideName"];
    NSNumber *totalNumberOfImages = [args objectForKey:@"totalNumberOfImages"];

    NSURLRequest *request = [NSURLRequest requestWithURL:[NSURL URLWithString:photourl]];

    AFHTTPRequestOperation *operation = [[AFHTTPRequestOperation alloc] initWithRequest:request];
    operation.inputStream = [NSInputStream inputStreamWithURL:[NSURL URLWithString:photourl]];

    [operation setShouldExecuteAsBackgroundTaskWithExpirationHandler:^{
        DLog(@"PROBLEMS_AF");
    }];
    DLog(@"URL_PHOTOURL: %@", photourl);
    DLog(@"indexSet: %@", operation.hasAcceptableStatusCode); 
    [operation  response];

    NSData *data = [args objectForKey:@"data"];

    NSString *path;
    path = [NSMutableString stringWithFormat:@"%@/Library/Application Support/Guides", NSHomeDirectory()];
    path = [path stringByAppendingPathComponent:guideName];
    NSString *guidePath = path;
    path = [path stringByAppendingPathComponent:photourl];

    if ([[NSFileManager defaultManager] fileExistsAtPath:guidePath]){
        [[NSFileManager defaultManager] createFileAtPath:path
                                                contents:data
                                              attributes:nil];
    }

    DLog(@"path: %@", path);
    operation.outputStream = [NSOutputStream outputStreamToFileAtPath:path append:NO];
    [operation start];


    DLog(@"isExecuting: %d",[operation isExecuting]);
    DLog(@"IS_FINISHED: %d",[operation isFinished]);


  }

} 

PhotoURL is the direct link to the image that I want to download.

Since this method is called for all the images, all logs is called several times, and seems to be correct.

like image 673
Joakim Engstrom Avatar asked Jun 25 '12 09:06

Joakim Engstrom


2 Answers

You have a few problems here. so first, why are you using @autoreleasepool? i think there is no need for this here. also, are you using ARC? i consider this, for the rest of my answer.

in AFNetworking there is a class called AFImageRequestOperation , so this would be a good idea for you to use. first, import it

#import "AFImageRequestOperation.h"

then you could create an object

NSURLRequest *request = [NSURLRequest requestWithURL:[NSURL URLWithString:photourl]];
AFImageRequestOperation *operation;
operation = [AFImageRequestOperation imageRequestOperationWithRequest:request 
    imageProcessingBlock:nil 
    cacheName:nil 
    success:^(NSURLRequest *request, NSHTTPURLResponse *response, UIImage *image) {

    } 
    failure:^(NSURLRequest *request, NSHTTPURLResponse *response, NSError *error) {
        NSLog(@"%@", [error localizedDescription]);
    }];

now, in the success block, you got the UIImage you need. there you need to get the documents directory. your code will not work on an ios device.

// Get dir
NSString *documentsDirectory = nil;
NSArray *paths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES);
documentsDirectory = [paths objectAtIndex:0];
NSString *pathString = [NSString stringWithFormat:@"%@/%@",documentsDirectory, guideName];

and then you could use NSDatas writeToFile

// Save Image
NSData *imageData = UIImageJPEGRepresentation(image, 90);
[imageData writeToFile:pathString atomically:YES];

at last, you need to start the operation

[operation start];

all together:

- (void)downloadImageInBackground:(NSDictionary *)args{

    NSString *guideName = [args objectForKey:@"guideName"];
    NSString *photourl = [args objectForKey:@"photoUrl"];

    NSURLRequest *request = [NSURLRequest requestWithURL:[NSURL URLWithString:photourl]];

    AFImageRequestOperation *operation = [AFImageRequestOperation imageRequestOperationWithRequest:request 
        imageProcessingBlock:nil 
        cacheName:nil 
        success:^(NSURLRequest *request, NSHTTPURLResponse *response, UIImage *image) {

            // Get dir
            NSString *documentsDirectory = nil;
            NSArray *paths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES);
            documentsDirectory = [paths objectAtIndex:0];
            NSString *pathString = [NSString stringWithFormat:@"%@/%@",documentsDirectory, guideName];

            // Save Image
            NSData *imageData = UIImageJPEGRepresentation(image, 90);
            [imageData writeToFile:pathString atomically:YES];

        } 
        failure:^(NSURLRequest *request, NSHTTPURLResponse *response, NSError *error) {
            NSLog(@"%@", [error localizedDescription]);
        }];

    [operation start];
}
like image 166
choise Avatar answered Oct 17 '22 04:10

choise


The problem here is, the operation is not retained. It will be deallocated immediately.

Either make the operation a property of your class or let a operation queue (also a property) handle the request for you (recommended). In the latter case don't call [operation start]. When you use AFHTTPClient the operation queue will also be managed for you.

Also you should register a completion callback for the request operation (setCompletionBlockWithSuccess:failure:).

like image 5
Felix Avatar answered Oct 17 '22 03:10

Felix