ImageClient2-asynch/CFNetworkLoader.m

/*
 
File: CFNetworkLoader.m
 
Abstract: CFNetwork ImageClient Sample
 
Version: 1.0
 
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MAKES NO WARRANTIES, EXPRESS OR IMPLIED, INCLUDING WITHOUT LIMITATION
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*/ 
 
#import "CFNetworkLoader.h"
#import "ImageClient.h"
#import "NSURLLoader.h"
 
#define BUFSIZE 4096
 
static void handleStreamEvent(CFReadStreamRef stream, CFStreamEventType type, void *clientCallBackInfo) {
    CFNetworkLoader *self = (CFNetworkLoader *)clientCallBackInfo;
    [self handleStreamEvent:type];
}
 
@implementation CFNetworkLoader
 
- (id)initWithImageClient:(ImageClient *)imgClient {
    if (self = [super init]) {
        imageClient = imgClient; // No retain because the ImageClient instance is retaining us
    }
    return self;
}
 
- (void)dealloc {
    if (request) CFRelease(request);
    [self cancelLoad];
    [super dealloc];
}
 
- (void)loadURL:(NSURL *)url {
    // set the request for the new transaction
    if (request) CFRelease(request);
    request = CFHTTPMessageCreateRequest(NULL, CFSTR("GET"), (CFURLRef)url, kCFHTTPVersion1_1);
    
    // Start the load
    [self loadRequest];
}
 
- (void)loadRequest {
    // Cancel any load currently in progress
    [self cancelLoad];
 
    // Start a fresh data to hold the downloaded image
    data = CFDataCreateMutable(NULL, 0);
    
    readStream = CFReadStreamCreateForHTTPRequest(NULL, request);
    
    CFStreamClientContext context = {0, self, NULL, NULL, NULL};
    CFReadStreamSetClient(readStream, kCFStreamEventHasBytesAvailable | kCFStreamEventEndEncountered | kCFStreamEventErrorOccurred, handleStreamEvent, &context);
    CFReadStreamScheduleWithRunLoop(readStream, CFRunLoopGetCurrent(), kCFRunLoopCommonModes);
 
    CFReadStreamOpen(readStream);
}
 
- (void)cancelLoad {
    if (readStream) {
        CFReadStreamClose(readStream);
        CFReadStreamSetClient(readStream, kCFStreamEventNone, NULL, NULL);
        CFReadStreamUnscheduleFromRunLoop(readStream, CFRunLoopGetCurrent(), kCFRunLoopCommonModes);
        CFRelease(readStream);
        readStream = NULL;
    }
    if (data) {
        CFRelease(data);
        data = NULL;
    }
}
 
// Callback for CFReadStream
- (void)handleStreamEvent:(CFStreamEventType)event {
    switch (event) {
        case kCFStreamEventHasBytesAvailable: {
            UInt8 buffer[BUFSIZE];
            int bytesRead = CFReadStreamRead(readStream, buffer, BUFSIZE);
            if (bytesRead > 0) {
                CFDataAppendBytes(data, buffer, bytesRead);
            }
            // Don't worry about bytesRead <= 0, because those will generate other events
            break;
        }
        case kCFStreamEventEndEncountered: 
            [imageClient setImageData:(NSData *)data];
            [self cancelLoad];
            break;
        case kCFStreamEventErrorOccurred:
            [imageClient errorOccurredLoadingImage];
            [self cancelLoad];
            break;
        default:
            NSLog(@"Received unexpected stream event %d\n", event);
    }
}
 
@end