(Objective-C) Facebook Download all Photos to Local Files

Demonstrates how to download all of one's Facebook photos to a local filesystem directory. This sample code keeps a local cache to avoid re-downloading the same photos twice. The program can be run again after a time, and it will download only photos that haven't yet been downloaded.

Chilkat Objective-C Library Downloads MAC OS X (Cocoa) Libs iOS Libs

#import <CkoCache.h>
#import <CkoOAuth2.h>
#import <CkoRest.h>
#import <NSString.h>
#import <CkoJsonObject.h>
#import <CkoStringArray.h>
#import <CkoStringBuilder.h>
#import <CkoHttp.h>
#import <CkoFileAccess.h>

// This example requires the Chilkat API to have been previously unlocked.
// See Global Unlock Sample for sample code.

// This example will use a local disk cache to avoid re-fetching the same
// photo id after it's been fetched once.
CkoCache *fbCache = [[CkoCache alloc] init];
// The cache will use 1 level of 256 sub-directories.
fbCache.Level = [NSNumber numberWithInt:1];
// Use a directory path that makes sense on your operating system..
[fbCache AddRoot: @"C:/fbCache"];

// This example assumes a previously obtained an access token
CkoOAuth2 *oauth2 = [[CkoOAuth2 alloc] init];
oauth2.AccessToken = @"FACEBOOK-ACCESS-TOKEN";

CkoRest *rest = [[CkoRest alloc] init];

// Connect to Facebook.
BOOL success = [rest Connect: @"graph.facebook.com" port: [NSNumber numberWithInt: 443] tls: YES autoReconnect: YES];
if (success != YES) {
    NSLog(@"%@",rest.LastErrorText);
    return;
}

// Provide the authentication credentials (i.e. the access key)
[rest SetAuthOAuth2: oauth2];

// There are two choices:  
// We can choose to download the photos the person is tagged in or has uploaded
// by setting type to "tagged" or "uploaded".
[rest AddQueryParam: @"type" value: @"uploaded"];

// To download all photos, we begin with an outer loop that iterates over
// the list of photo nodes in pages.  Each page returned contains a list of 
// photo node ids.  Each photo node id must be retrieved to get the download URL(s)
// of the actual image.

// I don't know the max limit for the number of records that can be downloaded at once.
[rest AddQueryParam: @"limit" value: @"100"];

// Get the 1st page of photos ids.
// See https://developers.facebook.com/docs/graph-api/reference/user/photos/ for more information.
NSString *responseJson = [rest FullRequestNoBody: @"GET" uriPath: @"/v2.7/me/photos"];
if (rest.LastMethodSuccess != YES) {
    NSLog(@"%@",rest.LastErrorText);
    return;
}

CkoJsonObject *photoJson = [[CkoJsonObject alloc] init];
CkoStringArray *saPhotoUrls = [[CkoStringArray alloc] init];
CkoStringBuilder *sbPhotoIdPath = [[CkoStringBuilder alloc] init];

CkoJsonObject *json = [[CkoJsonObject alloc] init];
json.EmitCompact = NO;
[json Load: responseJson];

int i;
NSString *photoId = 0;
NSString *imageUrl = 0;

// Get the "after" cursor.
NSString *afterCursor = [json StringOf: @"paging.cursors.after"];
while (json.LastMethodSuccess == YES) {

    NSLog(@"%@",@"-------------------");
    NSLog(@"%@%@",@"afterCursor = ",afterCursor);

    // For each photo id in this page...
    i = 0;
    int numItems = [[json SizeOfArray: @"data"] intValue];
    while (i < numItems) {
        json.I = [NSNumber numberWithInt: i];
        photoId = [json StringOf: @"data[i].id"];
        NSLog(@"%@%@",@"photoId = ",photoId);

        // We need to fetch the JSON for this photo.  Check to see if it's in the local disk cache,
        // and if not, then get it from Facebook.
        NSString *photoJsonStr = [fbCache FetchText: photoId];
        if (fbCache.LastMethodSuccess == NO) {
            // It's not locally available, so get it from Facebook..
            [sbPhotoIdPath Clear];
            [sbPhotoIdPath Append: @"/v2.7/"];
            [sbPhotoIdPath Append: photoId];

            [rest ClearAllQueryParams];
            [rest AddQueryParam: @"fields" value: @"id,album,images"];

            NSLog(@"%@",@"Fetching photo node from Facebook...");

            // This REST request will continue using the existing connection.
            // If the connection was closed, it will automatically reconnect to send the request.
            photoJsonStr = [rest FullRequestNoBody: @"GET" uriPath: [sbPhotoIdPath GetAsString]];
            if (rest.LastMethodSuccess != YES) {
                NSLog(@"%@",rest.LastErrorText);
                return;
            }

            // Add the photo JSON to the local cache.
            [fbCache SaveTextNoExpire: photoId eTag: @"" strData: photoJsonStr];
        }

        // Parse the photo JSON and add the main photo download URL to saPhotoUrls
        // There may be multiple URLs in the images array, but the 1st one is the largest and main photo URL.
        // The others are smaller sizes of the same photo.
        [photoJson Load: photoJsonStr];
        imageUrl = [photoJson StringOf: @"images[0].source"];
        if (photoJson.LastMethodSuccess == YES) {

            // Actually, we'll add a small JSON document that contains both the image ID and the URL.
            CkoJsonObject *imgUrlJson = [[CkoJsonObject alloc] init];
            [imgUrlJson AppendString: @"id" value: photoId];
            [imgUrlJson AppendString: @"url" value: imageUrl];
            [saPhotoUrls Append: [imgUrlJson Emit]];
            NSLog(@"%@%@",@"imageUrl = ",imageUrl);
        }

        i = i + 1;
    }

    // Prepare for getting the next page of photos ids.
    // We can continue using the same REST object.
    // If already connected, we'll continue using the existing connection.
    // Otherwise, a new connection will automatically be made if needed.
    [rest ClearAllQueryParams];
    [rest AddQueryParam: @"type" value: @"uploaded"];
    [rest AddQueryParam: @"limit" value: @"20"];
    [rest AddQueryParam: @"after" value: afterCursor];

    // Get the next page of photo ids.
    responseJson = [rest FullRequestNoBody: @"GET" uriPath: @"/v2.7/me/photos"];
    if (rest.LastMethodSuccess != YES) {
        NSLog(@"%@",rest.LastErrorText);
        return;
    }

    [json Load: responseJson];
    afterCursor = [json StringOf: @"paging.cursors.after"];
}

NSLog(@"%@",@"No more pages of photos.");

// Now iterate over the photo URLs and download each to a file.
// We can use Chilkat HTTP.  No Facebook authorization (access token) is required to download
// the photo once the URL is known.  
CkoHttp *http = [[CkoHttp alloc] init];

// We'll cache the image data so that if run again, we don't re-download the same image again.
int numUrls = [saPhotoUrls.Count intValue];
i = 0;
CkoJsonObject *urlJson = [[CkoJsonObject alloc] init];
NSData imageBytes;
CkoFileAccess *fac = [[CkoFileAccess alloc] init];

while (i < numUrls) {
    [urlJson Load: [saPhotoUrls GetString: [NSNumber numberWithInt: i]]];
    photoId = [urlJson StringOf: @"id"];
    imageUrl = [urlJson StringOf: @"url"];

    // Check the local cache for the image data.
    // Only download and save if not already cached.
    imageBytes = [fbCache FetchFromCache: imageUrl];
    if (fbCache.LastMethodSuccess == NO) {
        //  This photo needs to be downloaded.

        CkoStringBuilder *sbImageUrl = [[CkoStringBuilder alloc] init];
        [sbImageUrl Append: imageUrl];

        // Let's form a filename..
        NSString *extension = @".jpg";
        if ([sbImageUrl Contains: @".gif" caseSensitive: NO] == YES) {
            extension = @".gif";
        }

        if ([sbImageUrl Contains: @".png" caseSensitive: NO] == YES) {
            extension = @".png";
        }

        if ([sbImageUrl Contains: @".tiff" caseSensitive: NO] == YES) {
            extension = @".tiff";
        }

        if ([sbImageUrl Contains: @".bmp" caseSensitive: NO] == YES) {
            extension = @".bmp";
        }

        CkoStringBuilder *sbLocalFilePath = [[CkoStringBuilder alloc] init];
        [sbLocalFilePath Append: @"C:/Photos/facebook/uploaded/"];
        [sbLocalFilePath Append: photoId];
        [sbLocalFilePath Append: extension];

        imageBytes = [http QuickGet: imageUrl];
        if (http.LastMethodSuccess != YES) {
            NSLog(@"%@",http.LastErrorText);
            return;
        }

        // We've downloaded the photo image bytes into memory.
        // Save it to the cache AND save it to the output file.
        [fbCache SaveToCacheNoExpire: imageUrl eTag: @"" data: imageBytes];
        [fac WriteEntireFile: [sbLocalFilePath GetAsString] fileData: imageBytes];

        NSLog(@"%@%@",@"Downloaded to ",[sbLocalFilePath GetAsString]);
    }

    i = i + 1;
}

NSLog(@"%@",@"Finished downloading all Facebook photos!");