Download a file / image with AFNetworking in iOS?

Question

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

Answer 1

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];
}

Answer 2

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:).