(Objective-C) Download File from Dropbox (Streaming)

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Downloads a file from Dropbox, streaming it directly to a file in the filesystem.

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

#import <CkoRest.h>
#import <CkoJsonObject.h>
#import <CkoStream.h>
#import <NSString.h>
#import <CkoDateTime.h>
#import <CkoDtObj.h>

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

// A Dropbox access token should have been previously obtained.
// Dropbox access tokens do not expire.
// See Dropbox Access Token.

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

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

// Add request headers.
[rest AddHeader: @"Authorization" value: @"Bearer DROPBOX_ACCESS_TOKEN"];

// The download "parameters" are contained in JSON passed in an HTTP request header.
// This is the JSON indicating the file to be downloaded:
// { 
//    "path": "/Homework/lit/hamlet.xml",
// }

CkoJsonObject *json = [[CkoJsonObject alloc] init];
[json AppendString: @"path" value: @"/Homework/lit/hamlet.xml"];
[rest AddHeader: @"Dropbox-API-Arg" value: [json Emit]];

// Setup a file stream for the download
CkoStream *fileStream = [[CkoStream alloc] init];
fileStream.SinkFile = @"qa_output/hamletFromDropbox.xml";

// Indicate that the call to FullRequestNoBody should send the response body
// to fileStream if the response status code is 200.
// If a non-success response status code is received, then nothing
// is streamed to the output file and the error response is returned by FullRequestNoBody.
int expectedStatus = 200;
[rest SetResponseBodyStream: [NSNumber numberWithInt: expectedStatus] autoSetStreamCharset: YES responseStream: fileStream];

NSString *responseStr = [rest FullRequestNoBody: @"POST" uriPath: @"/2/files/download"];
if (rest.LastMethodSuccess != YES) {
    NSLog(@"%@",rest.LastErrorText);
    return;
}

// When successful, Dropbox responds with a 200 response code.
if ([rest.ResponseStatusCode intValue] != 200) {
    // Examine the request/response to see what happened.
    NSLog(@"%@%d",@"response status code = ",[rest.ResponseStatusCode intValue]);
    NSLog(@"%@%@",@"response status text = ",rest.ResponseStatusText);
    NSLog(@"%@%@",@"response header: ",rest.ResponseHeader);
    NSLog(@"%@%@",@"response body (if any): ",responseStr);
    NSLog(@"%@",@"---");
    NSLog(@"%@%@",@"LastRequestStartLine: ",rest.LastRequestStartLine);
    NSLog(@"%@%@",@"LastRequestHeader: ",rest.LastRequestHeader);
    return;
}

// Information about the downloaded file is also available as JSON in a response header.
// The "dropbox-api-result" response header contains the information.  For example:
NSString *apiResult = [rest ResponseHdrByName: @"dropbox-api-result"];
NSLog(@"%@",apiResult);

// In this case, the pretty-formatted dropbox-api-result JSON looks like this:
// { 
//   "name": "hamlet.xml",
//   "path_lower": "/homework/lit/hamlet.xml",
//   "path_display": "/Homework/lit/hamlet.xml",
//   "id": "id:74FkdeNuyKAAAAAAAAAAAQ",
//   "client_modified": "2016-06-02T23:19:00Z",
//   "server_modified": "2016-06-02T23:19:00Z",
//   "rev": "9482db15f",
//   "size": 279658
// }

// Load the JSON, pretty-print it, and demonstrate how to get some values...
CkoJsonObject *jsonResult = [[CkoJsonObject alloc] init];
jsonResult.EmitCompact = NO;
[jsonResult Load: apiResult];
// Show the JSON pretty-printed...
NSLog(@"%@",[jsonResult Emit]);

// Sample code to get data from the JSON response:
int size = [[jsonResult IntOf: @"size"] intValue];
NSLog(@"%@%d",@"size = ",size);

NSString *rev = [jsonResult StringOf: @"rev"];
NSLog(@"%@%@",@"rev = ",rev);

NSString *clientModified = [jsonResult StringOf: @"client_modified"];
CkoDateTime *ckdt = [[CkoDateTime alloc] init];
[ckdt SetFromTimestamp: clientModified];
BOOL bLocalTime = YES;
CkoDtObj *dt = [ckdt GetDtObj: bLocalTime];
NSLog(@"%d%@%d%@%d%@%d%@%d",[dt.Day intValue],@"/",[dt.Month intValue],@"/",[dt.Year intValue],@" ",[dt.Hour intValue]
    ,@":",[dt.Minute intValue]);