如何使用AWS iOS SDK从设备上传图像并设置为public

Question

Since it seems we are limited to the number of buckets, I'm trying to figure out how to accomplish the following:

• I have an iOS app, where users can upload a profile image.
• Profile image can be viewed by anyone (I want it public).
• Ideally, I can upload to a single bucket (for example: myprofilepics.s3.amazonaws.com)
• Ideally, Each user can upload to their own sub folder (for example: myprofilepics.s3.amazonaws.com/images/userXXX/
• Ideally, I upload the image, and set it to public access direct from the app so that other users can immediately view profile pics.

Am I missing something in the documentation? I appreciate any feedback on this issue.

Answer 1

To solve this problem, I started with Amazon's sample code in their iOS SDK, found here . In the SDK zip, the sample project of interest can be found at samples/S3_Uploader .

To get from that sample project to one in which the uploaded image is public, you simply need to add one line in the right place:

por.cannedACL   = [S3CannedACL publicRead];

where por is the S3PutObjectRequest used to upload the image.

My project's code for uploading looks like this (looks almost identical to Amazon's sample code):

NSString *uuid = @""; // Generate a UUID however you like, or use something else to name your image.
UIImage *image; // This is the UIImage you'd like to upload.

// This URL is not used in the example, but it points to the file
// to be uploaded.
NSString *url = [NSString pathWithComponents:@[ @"https://s3.amazonaws.com/", AWS_PICTURE_BUCKET, uuid ]];

// Convert the image to JPEG data. Use UIImagePNGRepresentation for pngs
NSData *imageData = UIImageJPEGRepresentation(image, 1.0);

// Create the S3 Client.
AmazonS3Client *s3 = [[AmazonS3Client alloc] initWithAccessKey:AWS_ACCESS_KEY_ID withSecretKey:AWS_SECRET_KEY];

@try {
    // Create the picture bucket.
    [s3 createBucket:[[S3CreateBucketRequest alloc] initWithName:AWS_PICTURE_BUCKET]];

    // Upload image data.  Remember to set the content type.
    S3PutObjectRequest *por = [[S3PutObjectRequest alloc] initWithKey:uuid inBucket:AWS_PICTURE_BUCKET];
    por.contentType = @"image/jpeg"; // use "image/png" here if you are uploading a png
    por.cannedACL   = [S3CannedACL publicRead];
    por.data        = imageData;
    por.delegate    = self; // Don't need this line if you don't care about hearing a response.

    // Put the image data into the specified s3 bucket and object.
    [s3 putObject:por];
}
@catch (AmazonClientException *exception) {
    NSLog(@"exception");
}

AWS_ACCESS_KEY_ID and AWS_SECRET_KEY are, of course, your AWS credentials, and AWS_PICTURE_BUCKET is your picture bucket.

Answer 2

If you are managing the identity of your own users - that is, not through AIM - you also have to manage what resources that have access to. I would slip in a thin web service that governs access to the files on S3.

Alternatively you can provide access to S3 for your users by using Temporary Security Credentials and a security policy. You would have to add code on the device to get the temporary tokens for your users.

I'd opt for the first solution as it keeps Amazon S3 out of the equation and your hands free to choose another backend at a later stage.

Answer 3

This is what I ended up doing:

    BOOL success = YES;

// Initialize the S3 Client.
AmazonS3Client *s3 = [[AmazonS3Client alloc] initWithAccessKey:ACCESS_KEY_ID withSecretKey:SECRET_KEY];

@try {
    // Create the picture bucket.
    [s3 createBucket:[[S3CreateBucketRequest alloc] initWithName:HOSTED_BUCKET]];

    NSString *remoteImagePath = [self pathWithImageType:SFHostedImageTypeProfile identiefier:@""];


    // Upload image data.  Remember to set the content type.
    S3PutObjectRequest *por = [[S3PutObjectRequest alloc] initWithKey:remoteImagePath inBucket:HOSTED_BUCKET];
    por.contentType = @"image/png";

    por.data        = UIImagePNGRepresentation(image);

    // Put the image data into the specified s3 bucket and object.
    [s3 putObject:por];
}
@catch (AmazonClientException *exception) {
    //        [Constants showAlertMessage:exception.message withTitle:@"Upload Error"];
    NSLog(@"Save Hosted Image Exception: %@", exception.message);

    success = NO;
}

return success;