EADemo/EADSessionController.m

/*
    Copyright (C) 2016 Apple Inc. All Rights Reserved.
    See LICENSE.txt for this sample’s licensing information
    
    Abstract:
    Provides an interface for communication with an EASession. Also the delegate for the EASession input and output stream objects.
 */
 
#import "EADSessionController.h"
@interface EADSessionController ()
 
@property (nonatomic, strong) EASession *session;
@property (nonatomic, strong) NSMutableData *writeData;
@property (nonatomic, strong) NSMutableData *readData;
 
@end
 
NSString *EADSessionDataReceivedNotification = @"EADSessionDataReceivedNotification";
 
@implementation EADSessionController
 
#pragma mark Internal
 
// low level write method - write data to the accessory while there is space available and data to write
- (void)_writeData {
    while (([[_session outputStream] hasSpaceAvailable]) && ([_writeData length] > 0))
    {
        NSInteger bytesWritten = [[_session outputStream] write:[_writeData bytes] maxLength:[_writeData length]];
        if (bytesWritten == -1)
        {
            NSLog(@"write error");
            break;
        }
        else if (bytesWritten > 0)
        {
            [_writeData replaceBytesInRange:NSMakeRange(0, bytesWritten) withBytes:NULL length:0];
            NSLog(@"bytesWritten %ld", (long)bytesWritten);
 
        }
    }
}
 
// low level read method - read data while there is data and space available in the input buffer
- (void)_readData {
#define EAD_INPUT_BUFFER_SIZE 128
    uint8_t buf[EAD_INPUT_BUFFER_SIZE];
    while ([[_session inputStream] hasBytesAvailable])
    {
        NSInteger bytesRead = [[_session inputStream] read:buf maxLength:EAD_INPUT_BUFFER_SIZE];
        if (_readData == nil) {
            _readData = [[NSMutableData alloc] init];
        }
        [_readData appendBytes:(void *)buf length:bytesRead];
        NSLog(@"read %ld bytes from input stream", (long)bytesRead);
    }
 
    [[NSNotificationCenter defaultCenter] postNotificationName:EADSessionDataReceivedNotification object:self userInfo:nil];
}
 
#pragma mark Public Methods
 
+ (EADSessionController *)sharedController
{
    static EADSessionController *sessionController = nil;
    if (sessionController == nil) {
        sessionController = [[EADSessionController alloc] init];
    }
 
    return sessionController;
}
 
- (void)dealloc
{
    [self closeSession];
    [self setupControllerForAccessory:nil withProtocolString:nil];
}
 
// initialize the accessory with the protocolString
- (void)setupControllerForAccessory:(EAAccessory *)accessory withProtocolString:(NSString *)protocolString
{
    NSLog(@"setupControllerForAccessory entered protocolString is %@", protocolString);
    _accessory = accessory;
    _protocolString = [protocolString copy];
}
 
// open a session with the accessory and set up the input and output stream on the default run loop
- (BOOL)openSession
{
    [_accessory setDelegate:self];
    _session = [[EASession alloc] initWithAccessory:_accessory forProtocol:_protocolString];
 
    if (_session)
    {
        [[_session inputStream] setDelegate:self];
        [[_session inputStream] scheduleInRunLoop:[NSRunLoop currentRunLoop] forMode:NSDefaultRunLoopMode];
        [[_session inputStream] open];
 
        [[_session outputStream] setDelegate:self];
        [[_session outputStream] scheduleInRunLoop:[NSRunLoop currentRunLoop] forMode:NSDefaultRunLoopMode];
        [[_session outputStream] open];
    }
    else
    {
        NSLog(@"creating session failed");
    }
 
    return (_session != nil);
}
 
// close the session with the accessory.
- (void)closeSession
{
    [[_session inputStream] close];
    [[_session inputStream] removeFromRunLoop:[NSRunLoop currentRunLoop] forMode:NSDefaultRunLoopMode];
    [[_session inputStream] setDelegate:nil];
    [[_session outputStream] close];
    [[_session outputStream] removeFromRunLoop:[NSRunLoop currentRunLoop] forMode:NSDefaultRunLoopMode];
    [[_session outputStream] setDelegate:nil];
 
    _session = nil;
 
    _writeData = nil;
    _readData = nil;
}
 
// high level write data method
- (void)writeData:(NSData *)data
{
    if (_writeData == nil) {
        _writeData = [[NSMutableData alloc] init];
    }
 
    [_writeData appendData:data];
    [self _writeData];
}
 
// high level read method 
- (NSData *)readData:(NSUInteger)bytesToRead
{
    NSData *data = nil;
    if ([_readData length] >= bytesToRead) {
        NSRange range = NSMakeRange(0, bytesToRead);
        data = [_readData subdataWithRange:range];
        [_readData replaceBytesInRange:range withBytes:NULL length:0];
    }
    return data;
}
 
// get number of bytes read into local buffer
- (NSUInteger)readBytesAvailable
{
    return [_readData length];
}
 
#pragma mark EAAccessoryDelegate
- (void)accessoryDidDisconnect:(EAAccessory *)accessory
{
    // do something ...
}
 
#pragma mark NSStreamDelegateEventExtensions
 
// asynchronous NSStream handleEvent method
- (void)stream:(NSStream *)aStream handleEvent:(NSStreamEvent)eventCode
{
    switch (eventCode) {
        case NSStreamEventNone:
            break;
        case NSStreamEventOpenCompleted:
            break;
        case NSStreamEventHasBytesAvailable:
            [self _readData];
            break;
        case NSStreamEventHasSpaceAvailable:
            [self _writeData];
            break;
        case NSStreamEventErrorOccurred:
            break;
        case NSStreamEventEndEncountered:
            break;
        default:
            break;
    }
}
 
@end


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