下载的图像在文档目录中的字节数为零

Question

I am trying to download and store image from webURL to Document Directory.
Here is my code for that.

-(void)downloadPersonPhoto:(NSDictionary *)dict
{
    NSString *imageUrlStr=[dict objectForKey:@"personPhoto"];
    if ([[dict valueForKey:@"personAvatarStore"] isEqualToString:@"AMAZON"])
    {
        imageUrlStr = [imageUrlStr stringByReplacingOccurrencesOfString:@"original" withString:@"100x100"];
    }
    NSFileManager *fileManager = [NSFileManager defaultManager];
    NSString *documentsDirectory = [self getDocumentDirectory];
    NSString *dataPath = [documentsDirectory stringByAppendingPathComponent:@"personPhoto"];
    if (![fileManager fileExistsAtPath:dataPath]) {
        [fileManager createDirectoryAtPath:dataPath withIntermediateDirectories:NO attributes:nil error:nil]; //Create folder
    }
    NSString *fullPath = [dataPath stringByAppendingPathComponent:[NSString stringWithFormat:@"%@.png",[dict valueForKey:@"personId"]]];
    if (![fileManager fileExistsAtPath:fullPath]) {
        NSData *imageData = [NSData dataWithContentsOfURL:[NSURL URLWithString:imageUrlStr]];
        [fileManager createFileAtPath:fullPath contents:imageData attributes:nil];
        NSLog(@"Avatar Photo stored at: %@", fullPath);
    }
}

Every time "Avatar photo stored at : ..." is going to print in console. But if I go to that path and check image then it has zero bytes of size and no any preview available.
webURL of image is correct I can also check from web Browser. I don't know where is mistake in my code.
Can you please help me to solve this??
Thanks in advance.

Answer 1

dataWithContentsOfURL is not download image asynchronously from server. now if imagesize is big enough then it takes some time for downloading. and you are directly trying to store image to document directory. I think that create problem. you should use NSUrlSession for getting image and you should write data to local storage like documents directory from completion handler of NSUrlSession method call. you can use AFNetworking also to manage this kind od stuff.

Second thing use

 [data writeToFile:path atomically:NO];

to store data to document directory and path is final path and should be unique for different data.

Answer 2

[NSData dataWithContentsOfURL] is not a asynchronously method

if you Debug you code you will find imagedata will be nil

you should first get imagedata then store it

you can use AFNetworing , SDWebImage framework or just use NSURLSession download it

here's one solution of my own

[[NSURLSession sharedSession] dataTaskWithURL:url completionHandler:^(NSData *data, NSURLResponse *response, NSError * error) { //error if (error) { //handle error return; } if (data) { //store imagedata [data writeToFile:filepath atomically:NO]; } }];

good day :)