How do I download a file from S3 to an iPhone application? - iphone

Question

I am new to iPhone development. I am developing an iPhone application which needs to open files stored on Amazon's S3 service.
How do I download a file from S3 to my iPhone application? I have tried Amazon's SDK, but they don't seem to provide a means of downloading and saving a file. How do I go about obtaining a file's URL from S3 and saving it in my application?

Answer 1

I always use the ASIHttpRequest library to do this and it's quite simple, here's a sample code from their website:
NSString *secretAccessKey = #"my-secret-access-key";
NSString *accessKey = #"my-access-key";
NSString *bucket = #"my-bucket";
NSString *path = #"path/to/the/object";
ASIS3ObjectRequest *request = [ASIS3ObjectRequest requestWithBucket:bucket key:path];
[request setSecretAccessKey:secretAccessKey];
[request setAccessKey:accessKey];
[request startSynchronous];
if (![request error]) {
NSData *data = [request responseData];
} else {
NSLog(#"%#",[[request error] localizedDescription]);
}
You can't get easier than this :)

Answer 2

If you don't have the luxury of simplicity using ASI, and/or are stuck with AWSiOS SDK, it's not a lot different:
/* borrowed from Maurício Linhares's answer */
NSString *secretAccessKey = #"my-secret-access-key";
NSString *accessKey = #"my-access-key";
NSString *bucket = #"my-bucket";
NSString *path = #"path/to/the/object";
/********************************************/
AmazonCredentials *credentials = [[AmazonCredentials alloc] initWithAccessKey: accessKey withSecretKey: secretAccessKey];
AmazonS3Client *connection = [[AmazonS3Client alloc] initWithCredentials: credentials];
S3GetObjectRequest *downloadRequest = [[[S3GetObjectRequest alloc] initWithKey:path withBucket: bucket] autorelease];
[downloadRequest setDelegate: self]; /* only needed for delegate (see below) */
S3GetObjectResponse *downloadResponse = [self.awsConnection getObject: downloadRequest];
Then you can look at downloadResponse.body and downloadResponse.httpStatusCode, preferable in a delegate:
-(void)request: (S3Request *)request didCompleteWithResponse: (S3Response *) response {
NSLog(#"Download finished (%d)",response.httpStatusCode);
/* do something with response.body and response.httpStatusCode */
/* if you have multiple requests, you can check request arg */
}