How to read SD card contents through iPad Camera Connection Kit in iOS SDK?

Question

I want to read the SD card contents through iPad Camera Connection Kit in iOS SDK, how to do that ? Any code sample ?

Thanks.

Answer 1

Use External Accessory Framework first you need to register for notifications in view did load-

[[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(_accessoryDidConnect:) name:EAAccessoryDidConnectNotification object:nil];
[[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(_accessoryDidDisconnect:) name:EAAccessoryDidDisconnectNotification object:nil];
[[EAAccessoryManager sharedAccessoryManager] registerForLocalNotifications];


Then you should find the attached accessories -


     _accessoryList = [[NSMutableArray alloc] initWithArray:[[EAAccessoryManager sharedAccessoryManager] connectedAccessories]];


Then check this is the correct accessory you are looking for -

for(EAAccessory *obj in _accessoryList)
    {
        if ([[obj protocolStrings] containsObject:@"com.bluebamboo.p25i"])//if find the accessory(p25) record it
        {
            [accessoryLabel setText:@"P25mi connected"]; // yup this is correct accessory!
            [obj release];
            break;
        }
    }

Then open a session -

//if accessory not null
if(accessory)
{
    session = [[EASession alloc] initWithAccessory:accessory forProtocol:@"com.bluebamboo.p25i"];//initial session that pair with protocol string
    [[session outputStream] setDelegate:self];//set delegate class for output stream 
    [[session outputStream] scheduleInRunLoop:[NSRunLoop currentRunLoop] forMode:NSDefaultRunLoopMode]; //set outputstream loop
    [[session outputStream] open]; //open session
    [[session inputStream] setDelegate:self];
    [[session inputStream] open];
    [[session inputStream] scheduleInRunLoop:[NSRunLoop currentRunLoop] forMode:NSDefaultRunLoopMode];


}

Then the stream delegate will be called -

//this is a stream listener function that would actived by system while steam has any event
- (void)stream:(NSStream *)theStream handleEvent:(NSStreamEvent)streamEvent
{   



    switch(streamEvent)
    {
        case NSStreamEventOpenCompleted:
            if(theStream==[session outputStream])//to identify which stream has been opend
            {
                [self addLabel:@"outputNSStream open;"];
            }
            else
            {
                [self addLabel:@"inputNSStream open:"];
            }


            break;
        case NSStreamEventHasBytesAvailable:
            //if system has stream data comes in
            [self addLabel:@"receiving Data;"];

            uint8_t buf2[100];//create a buffer
            unsigned int len = 0;
            //read buffer commands return actuall length of return data
            len = [[session inputStream] read:buf2 maxLength:100];

            if (len>0 )
            {
                if (buf2[4]==0x03&&buf2[5]==0x00)//if two bytes are 0x03 and 0x00, that means print success 
                {
                    //display success message
                    alertMessage = [[UIAlertView alloc] initWithTitle:@"SUCCESS:" message:@"P25i have printed Text successfully" delegate:nil cancelButtonTitle:@"OK" otherButtonTitles:nil];
                    [alertMessage show];
                    [alertMessage release];

                    [self addLabel:@"received success"]; 
                }

            }


            [self enableButton];
            //operation finished then close all streams and session
            [[session outputStream] close];
            [[session outputStream] removeFromRunLoop:[NSRunLoop currentRunLoop] forMode:NSDefaultRunLoopMode];
            [[session outputStream] setDelegate:nil];
            [[session inputStream] close];
            [[session inputStream] removeFromRunLoop:[NSRunLoop currentRunLoop] forMode:NSDefaultRunLoopMode];
            [[session inputStream] setDelegate:nil];
            [session release];
            session = nil;
            //[self connectSession];
            //switcher2=TRUE;

            break;
        case NSStreamEventHasSpaceAvailable:

            [self addLabel:@" NSStreamEventHasSpaceAvailable"];
            if (switcher2)//we send loop mode so application would keep sending data to p25, the switcher2 identify the data has send to P25m
            {


                         //[self addLabel:@"buffer is selected"];
                 int contentLength=[printContent.text length];
                 unsigned char buffer[contentLength+7];
                 buffer[0] = 0X55; 
                         buffer[1]=0x66; 
                         buffer[2]=0x77;  
                         buffer[3]=0x88; 
                         buffer[4]=0x44;//print command
                for (int i=5;i