(Objective-C) Amazon S3 List More than 1000 Objects in Bucket

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S3 limits the size of the "List Objects" response to 1000 objects. To retrieve a listing of all of the objects in a bucket containing more than 1000 objects, we'll need to send several requests using continuation tokens.

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#import <CkoHttp.h>
#import <CkoStringBuilder.h>
#import <CkoXml.h>
#import <NSString.h>
#import <CkoDateTime.h>
#import <CkoDtObj.h>

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

CkoHttp *http = [[CkoHttp alloc] init];

// Insert your access key here:
http.AwsAccessKey = @"AWS_ACCESS_KEY";

// Insert your secret key here:
http.AwsSecretKey = @"AWS_SECRET_KEY";

// For the example, we'll get a listing containing approx. 25 objects
// using continuation tokens with an artificially low max-keys set to 5.
// (You may omit the max-keys query parameter to get the default 1000 maximum
// number of keys per request.)

CkoStringBuilder *sbContinuationToken = [[CkoStringBuilder alloc] init];
BOOL bGetMore = YES;
CkoStringBuilder *sbUri = [[CkoStringBuilder alloc] init];
CkoXml *xml = [[CkoXml alloc] init];
BOOL success;
NSString *itemKey = 0;
NSString *itemSizeDecimalStr = 0;
NSString *lastModTimestamp = 0;
CkoDateTime *dt = [[CkoDateTime alloc] init];

while (bGetMore == YES) {

    // Make sure to set the "list-type" query param equal to "2".
    // This chooses the GET Bucket (List Objects) Version 2 of the method.

    // IMPORTANT: You must include the max-keys param to get a response with a continuation token.
    // S3 limits the number of objects in a single response to 1000. Therefore, your max-keys
    // can be up to 1000.  If, for example, you have 2000 objects and do not specify
    // max-keys, then the response will contain 1000 objects with no continuation token. 
    [sbUri SetString: @"chilkat100?list-type=2&max-keys=5"];
    if ([sbContinuationToken.Length intValue] > 0) {
        [sbUri Append: @"&continuation-token="];
        [sbUri Append: [sbContinuationToken GetEncoded: @"url" charset: @"utf-8"]];
    }

    NSString *strXml = [http S3_ListBucketObjects: [sbUri GetAsString]];
    if (http.LastMethodSuccess != YES) {
        NSLog(@"%@",http.LastErrorText);
        return;
    }

    NSLog(@"%@%d",@"Response status code = ",[http.LastStatus intValue]);

    success = [xml LoadXml: strXml];
    if (success != YES) {
        NSLog(@"%@",xml.LastErrorText);
        return;
    }

    // If the response status code was not 200, then the XML response is not a 
    // listing of objects, but instead contains error information.
    if ([http.LastStatus intValue] != 200) {
        NSLog(@"%@",[xml GetXml]);
        NSLog(@"%@",@"Failed.");
        return;
    }

    // If this is not the final response, then we'll get an XML response that begins
    // like this.  (The IsTruncated child will be "true", and the NextContinuationToken
    // will have a value to be used in the next request.)
    // 	<?xml version="1.0" encoding="UTF-8" ?>
    // 	<ListBucketResult xmlns="http://s3.amazonaws.com/doc/2006-03-01/">
    // 	    <Name>chilkat100</Name>
    // 	    <Prefix />
    // 	    <NextContinuationToken>1Mlcx+W9OKsr8cxp3DP6r71wgsTUMj0vqlntWoaJKNbYdrauLdf40LsUdBeSYGFhzbGIHdcf5DSLcEBWbqG+1fW1UcQkUW1V4qgQONAKOwb8y8vOLJAQ8iQ==</NextContinuationToken>
    // 	    <KeyCount>5</KeyCount>
    // 	    <MaxKeys>5</MaxKeys>
    // 	    <IsTruncated>true</IsTruncated>
    // 	

    // Iterate over the bucket items in this chunk get information for each..
    int numItems = [[xml NumChildrenHavingTag: @"Contents"] intValue];
    NSLog(@"%@%d",@"Number of bucket items = ",numItems);

    int i = 0;
    while (i < numItems) {
        xml.I = [NSNumber numberWithInt: i];

        itemKey = [xml GetChildContent: @"Contents[i]|Key"];
        itemSizeDecimalStr = [xml GetChildContent: @"Contents[i]|Size"];
        lastModTimestamp = [xml GetChildContent: @"Contents[i]|LastModified"];

        [dt SetFromRfc822: lastModTimestamp];
        // Get a local date/time.
        BOOL bLocal = YES;
        CkoDtObj *dtObj = [dt GetDtObj: bLocal];

        NSLog(@"%d%@%@%@%@%@%d%@%d%@%d%@%d%@%d",i,@": ",itemKey,@", ",itemSizeDecimalStr,@", ",[dtObj.Day intValue],@"-"
            ,[dtObj.Month intValue],@"-",[dtObj.Year intValue],@":",[dtObj.Hour intValue],@":",[dtObj.Minute intValue]);

        i = i + 1;
    }

    // Check IsTruncated.
    bGetMore = NO;
    if ([xml ChildContentMatches: @"IsTruncated" pattern: @"true" caseSensitive: YES] == YES) {
        [sbContinuationToken SetString: [xml GetChildContent: @"NextContinuationToken"]];
        if ([sbContinuationToken.Length intValue] > 0) {
            bGetMore = YES;
        }

    }

}

// The output of this example (when tested) was:

// Response status code = 200
// Number of bucket items = 5
// 0: Abc.ics, 1833, 25-5-2011:9:53
// 1: Corpse Bride film poster.jpg, 53481, 6-9-2016:13:32
// 2: chiliPepper.gif, 7718, 12-3-2017:12:18
// 3: chilkatdude.jpg, 35137, 20-5-2011:16:14
// 4: cloud.search/dfe/indexer/pscc/2016/3/28/id,x-2-15-0-25-87-0.json, 1238, 2-4-2016:12:0
// Response status code = 200
// Number of bucket items = 5
// 0: cloud.search/dfe/indexer/pscc/2016/3/28/idx-2-15-0-25-87-0.json, 1238, 2-4-2016:11:33
// 1: dude.gif, 6373, 25-5-2011:17:29
// 2: french.txt, 47, 12-3-2017:12:18
// 3: hamlet.xml, 279658, 2-5-2016:12:21
// 4: hamlet_play.xml, 279658, 20-3-2017:8:22
// Response status code = 200
// Number of bucket items = 5
// 0: images/sea_creatures/starfish123.jpg, 6229, 19-1-2017:10:45
// 1: images/sea_creatures/starfishåäö.jpg, 6229, 19-1-2017:12:7
// 2: new folder/, 0, 26-11-2014:12:36
// 3: new_starfish.jpg, 6229, 20-3-2017:8:22
// 4: pigs.xml, 2804, 20-3-2017:8:22
// Response status code = 200
// Number of bucket items = 5
// 0: somethingBig.zip, 13089458, 26-9-2016:9:29
// 1: starfish.jpg, 6229, 12-3-2017:12:18
// 2: starfish/, 0, 10-11-2014:10:7
// 3: starfish/starfish.jpg, 6229, 10-11-2014:10:8
// 4: starfish/starfish2.jpg, 6229, 19-11-2014:10:36
// Response status code = 200
// Number of bucket items = 5
// 0: starfish/starfish3.jpg, 6229, 24-11-2014:14:33
// 1: starfish2.jpg, 5987, 20-4-2012:12:6
// 2: starfish3.jpg, 5987, 11-4-2012:7:10
// 3: starfishA.jpg, 6229, 10-5-2016:8:44
// 4: starfishCust.jpg, 6229, 12-11-2014:18:25
// Response status code = 200
// Number of bucket items = 1
// 0: xyz.ics, 1833, 25-5-2011:8:52
// 
//