Implementing SimpleFTPSample in swift - objective-c

Question

I am trying to convert an Objective-C app to swift.
I am reaching the part where I need to send a file through FTP to a distant server. I was able to to that in Objective-C but only because I had the SimpleFTPSample project that apple made to help the developers.
Right now I have almost complete the conversion between the two language but I am stuck.
I need to convert that code (from SimpleFTPSample+personal):
- (void)stream:(NSStream *)aStream handleEvent:(NSStreamEvent)eventCode
// An NSStream delegate callback that's called when events happen on our
// network stream.
{
#pragma unused(aStream)
assert(aStream == self.networkStream);
switch (eventCode) {
case NSStreamEventOpenCompleted: {
[self updateStatus:#"Opened connection"];
} break;
case NSStreamEventHasBytesAvailable: {
assert(NO); // should never happen for the output stream
} break;
case NSStreamEventHasSpaceAvailable: {
[self updateStatus:#"Sending"];
// If we don't have any data buffered, go read the next chunk of data.
if (self.bufferOffset == self.bufferLimit) {
NSInteger bytesRead;
bytesRead = [self.fileStream read:self.buffer maxLength:kSendBufferSize];
if (bytesRead == -1) {
[self stopSendWithStatus:#"File read error"];
} else if (bytesRead == 0) {
[self stopSendWithStatus:nil];
} else {
self.bufferOffset = 0;
self.bufferLimit = bytesRead;
}
}
// If we're not out of data completely, send the next chunk.
if (self.bufferOffset != self.bufferLimit) {
NSInteger bytesWritten;
bytesWritten = [self.networkStream write:&self.buffer[self.bufferOffset] maxLength:self.bufferLimit - self.bufferOffset];
assert(bytesWritten != 0);
if (bytesWritten == -1) {
[self stopSendWithStatus:#"Network write error"];
} else {
self.bufferOffset += bytesWritten;
}
}
} break;
case NSStreamEventErrorOccurred: {
[self stopSendWithStatus:#"Stream open error"];
} break;
case NSStreamEventEndEncountered: {
// ignore
} break;
default: {
assert(NO);
} break;
}
}
For now I managed to do that :
// An NSStream delegate callback that's called when events happen on our
// network stream.
func stream(theStream: NSStream!, handleEvent streamEvent: NSStreamEvent) {
switch (streamEvent) {
case NSStreamEvent.OpenCompleted:
println("Opened connection")
case NSStreamEvent.HasBytesAvailable:
println("Not suposed to happend")
case NSStreamEvent.HasSpaceAvailable:
println("Sending")
// If we don't have any data buffered, go read the next chunk of data.
if self.bufferOffset == self.bufferLimit {
var bytesRead: Int
bytesRead = self.fileStream.read(self.buffer, maxLength: 32768)
if bytesRead == -1 { self.stopSendWithStatus("File read error") }
else if bytesRead == 0 { self.stopSendWithStatus(nil) }
else {
self.bufferOffset = 0
self.bufferLimit = size_t(bytesRead)
}
}
// If we're not out of data completely, send the next chunk.
if self.bufferOffset != self.bufferLimit {
var bytesWritten: Int
bytesWritten = self.networkStream.write(&self.buffer[self.bufferOffset], maxLength: self.bufferLimit - self.bufferOffset)
if bytesWritten == -1 { self.stopSendWithStatus("Network write error") }
else { self.bufferOffset += size_t(bytesWritten) }
}
case NSStreamEvent.ErrorOccurred:
self.stopSendWithStatus("Stream open error")
case NSStreamEvent.EndEncountered:
println("ignore")
default:
println("default")
}
}
The kind of the used variables is :
var isSending = Bool()
var networkStream: NSOutputStream! = NSOutputStream()
var fileStream: NSInputStream! = NSInputStream()
var buffer: CConstPointer<UInt8>
var bufferOffset = size_t()
var bufferLimit = size_t()
I am stuck for the if self.bufferOffset != self.bufferLimit part.
Apparently &self.buffer[self.bufferOffset] is not correct (does not have a member name subscript), as well as self.bufferLimit - self.bufferOffset (could not find an overload '-' that accepts the supplied arguments)
To be honest I am not even sure to get what &self.buffer[self.bufferOffset] means. (not the variable but the notation.
So if someone has an idea on how to fixe that, he will be very welcomed !
You can find the SimpleFTPSample project here.
Sorry if my english is not perfect.

Answer 1

Can't you just compile SimpleFTP into a framework and use its methods directly from swift? No need to rewrite everything, Xcode does that for you. I use that for many custom libraries and it works like a charm. Just add target, and put in the required frameworks, include the framework and you're all set!

Answer 2

Here is my plagiarism of apple's SimpleFTPExample to solve my problem of uploading a csv file from an iOS app to a ftp server.
I took the PutController objective-c file, cut lots and lots (too much?) out of it an included it into my swift application.
I modified the parameters passed to the main PutController function, to pass in the data I wanted to send, the URL it has to go to and the username and password to get onto the server.
The cut down PutController.m
#import "PutController.h"
#include <CFNetwork/CFNetwork.h>
enum {
kSendBufferSize = 32768
};
#interface PutController () <NSStreamDelegate>
#property (nonatomic, strong, readwrite) NSOutputStream * networkStream;
#property (nonatomic, strong, readwrite) NSInputStream * fileStream;
#property (nonatomic, assign, readonly ) uint8_t * buffer;
#property (nonatomic, assign, readwrite) size_t bufferOffset;
#property (nonatomic, assign, readwrite) size_t bufferLimit;
#end
#implementation PutController
{
uint8_t _buffer[kSendBufferSize];
}
// Because buffer is declared as an array, you have to use a custom getter.
// A synthesised getter doesn't compile.
- (uint8_t *)buffer
{
return self->_buffer;
}
- (void)startSend:(NSData *)dataToUpload withURL:(NSURL *)toURL withUsername:(NSString *)username andPassword:(NSString *)password
{
printf(__FUNCTION__);
self.fileStream = [NSInputStream inputStreamWithData:dataToUpload];
[self.fileStream open];
// Open a CFFTPStream for the URL.
self.networkStream = CFBridgingRelease(
CFWriteStreamCreateWithFTPURL(NULL, (__bridge CFURLRef) toURL)
);
[self.networkStream setProperty:username forKey:(id)kCFStreamPropertyFTPUserName];
[self.networkStream setProperty:password forKey:(id)kCFStreamPropertyFTPPassword];
self.networkStream.delegate = self;
[self.networkStream scheduleInRunLoop:[NSRunLoop currentRunLoop] forMode:NSDefaultRunLoopMode];
[self.networkStream open];
}
- (void)stopSendWithStatus:(NSString *)statusString
{
printf(__FUNCTION__);
if (self.networkStream != nil) {
[self.networkStream removeFromRunLoop:[NSRunLoop currentRunLoop] forMode:NSDefaultRunLoopMode];
self.networkStream.delegate = nil;
[self.networkStream close];
self.networkStream = nil;
}
if (self.fileStream != nil) {
[self.fileStream close];
self.fileStream = nil;
}
}
- (void)stream:(NSStream *)aStream handleEvent:(NSStreamEvent)eventCode
// An NSStream delegate callback that's called when events happen on our
// network stream.
{
printf(__FUNCTION__);
switch (eventCode) {
case NSStreamEventOpenCompleted: {
printf("Opened connection");
} break;
case NSStreamEventHasBytesAvailable: {
printf("should never happen for the output stream");
} break;
case NSStreamEventHasSpaceAvailable: {
printf("Sending");
// If we don't have any data buffered, go read the next chunk of data.
if (self.bufferOffset == self.bufferLimit) {
NSInteger bytesRead;
bytesRead = [self.fileStream read:self.buffer maxLength:kSendBufferSize];
if (bytesRead == -1) {
[self stopSendWithStatus:#"File read error"];
} else if (bytesRead == 0) {
[self stopSendWithStatus:nil];
} else {
self.bufferOffset = 0;
self.bufferLimit = bytesRead;
}
}
// If we're not out of data completely, send the next chunk.
if (self.bufferOffset != self.bufferLimit) {
NSInteger bytesWritten;
bytesWritten = [self.networkStream write:&self.buffer[self.bufferOffset] maxLength:self.bufferLimit - self.bufferOffset];
assert(bytesWritten != 0);
if (bytesWritten == -1) {
[self stopSendWithStatus:#"Network write error"];
} else {
self.bufferOffset += bytesWritten;
}
}
} break;
case NSStreamEventErrorOccurred: {
[self stopSendWithStatus:#"Stream open error"];
} break;
case NSStreamEventEndEncountered: {
// ignore
} break;
default: {
assert(NO);
} break;
}
}
#end
Then the PutController.h
#import <UIKit/UIKit.h>
#interface PutController : NSObject
- (void)startSend:(NSData *)dataToUpload withURL:(NSURL *)toURL withUsername:(NSString *)username andPassword:(NSString *)password;
#end
This is the bridging file, that is project wide, to allow the swift application to pick up the objective-C header files. The objective-C code detail can then be mostly ignored. It really is one line.
// PlantRoomChecks-Bridging-Header.h
//
// Use this file to import your target's public headers that you would like to expose to Swift.
//
#import "PutController.h"
This is my project file that call the PutController. I have cut it to show just the relevant parts.
// Showing that I am not including any networking libraries
import UIKit
import CoreGraphics
class GraphVC: UIViewController {
var sendFile : PutController = PutController()
let username = "arthur_dent"
let password = "six_times_seven"
func saveData(){
var filename = "ftp://www.domain.co.uk/subdirectory/datafile"
// Converting the messing filename into one that can be used as a URL
let convertedStringForURL = filename.stringByAddingPercentEscapesUsingEncoding(NSUTF8StringEncoding)
let uploadUrl = NSURL(string: convertedStringForURL!)
Let dataForFile : NSData = dataFromElseWhere
let dataToUpload = dataForFile.dataUsingEncoding(NSUTF8StringEncoding, allowLossyConversion: false)
// USE THE OBJECTIVE-C VARIABLE
sendFile.startSend(dataToUpload, withURL: uploadUrl, withUsername: username, andPassword: password)
}