使用NSXMLParser initWithStream：没有接收到解析器委托方法 [英] Using NSXMLParser initWithStream: no parser delegate methods received
问题描述
我工作的基本问题是使用 NSStream 类来解析传入的增量XML数据。数据永远不是一个完整的XML文档，但我想根据插槽可以读取多少来接收和处理它。增加的块数。
The basic problem I'm working on is using the NSStream classes to parse incoming incremental XML data. The data is never a complete XML Document, but I want to receive and process it in incremental chunks based off how much ever the socket can read.
查看文档 NSXMLParser ，它似乎是 initWithStream：方法来初始化 NSXMLParser 将是我的问题的完美解决方案。我可以用 NSInputStream 初始化解析器，然后在上调用 parse 方法NSXMLParser 每当我通过我的套接字接收数据，然后应该调用 NSXMLParser 代理。
Looking at the documentation for NSXMLParser, it seems like the initWithStream: method to initialize a NSXMLParser would be the perfect solution to my problem. I can initialize the parser with a NSInputStream and then call the parse method on NSXMLParser whenever I receive data over my socket which should in turn call the NSXMLParser delegates.
，我没有看到任何代理被调用，唯一的方法，我看到被调用是流委托 stream：handleEvent：。从苹果或其他开发人员看来，这个API似乎没有什么例子。任何想法，我做错了或如何使用 initWithStream：正确？
However, I'm not seeing any of the delegates being called, the only method I see being called is the stream delegate stream:handleEvent:. There seems to be little to no examples of this API from Apple or other developers. Any ideas on what I'm doing wrong or how to use initWithStream: correctly?
ContentParser.h
@interface ContentParser : NSObject <NSStreamDelegate,
NSXMLParserDelegate>
{
NSInputStream *inputStream;
NSOutputStream *outputStream;
NSMutableData *receivedData;
NSXMLParser *xmlParser;
}
- (void)initStream;
ContentParser.m
@implementation ContentParser
- (void)initStream
{
CFReadStreamRef readStream;
CFWriteStreamRef writeStream;
CFStreamCreatePairWithSocketToHost(kCFAllocatorDefault,
(CFStringRef)@"<hostname>",
<port>,
&readStream,
&writeStream);
inputStream = (__bridge NSInputStream *)readStream;
outputStream = (__bridge NSOutputStream *)writeStream;
inputStream.delegate = self;
outputStream.delegate = self;
[inputStream scheduleInRunLoop:[NSRunLoop currentRunLoop]
forMode:NSDefaultRunLoopMode];
[outputStream scheduleInRunLoop:[NSRunLoop currentRunLoop]
forMode:NSDefaultRunLoopMode];
[inputStream open];
[outputStream open];
xmlParser = [[NSXMLParser alloc] initWithStream:inputStream];
[xmlParser setDelegate:self];
}
- (void)parser:(NSXMLParser *)parser didStartElement:(NSString *)elementName
namespaceURI:(NSString *)namespaceURI
qualifiedName:(NSString *)qName
attributes:(NSDictionary *)attributeDict
{
NSLog(@"didStartElement: %@, attributeDict: %@", elementName, attributeDict);
}
- (void)parser:(NSXMLParser *)parser foundCharacters:(NSString *)string
{
NSLog(@"foundCharacters: %@", string);
}
- (void)parser:(NSXMLParser *)parser didEndElement:(NSString *)elementName
namespaceURI:(NSString *)namespaceURI
qualifiedName:(NSString *)qName
{
NSLog(@"didEndElement: %@", elementName);
}
- (void)parser:(NSXMLParser *)parser parseErrorOccurred:(NSError *)parseError
{
NSLog(@"Error %ld, Description: %@, Line: %ld, Column: %ld",
[parseError code], [[parser parserError] localizedDescription],
[parser lineNumber], [parser columnNumber]);
}
- (void)stream:(NSStream *)stream handleEvent:(NSStreamEvent)eventCode
{
switch (eventCode) {
case NSStreamEventHasBytesAvailable:
{
if (stream == inputStream) {
NSInputStream *is = (NSInputStream *)stream;
if (receivedData == nil) {
receivedData = [[NSMutableData alloc] init];
}
uint8_t buf[1024];
NSInteger bytesRead = [is read:buf maxLength:1024];
if (bytesRead == -1) {
NSLog(@"Network read error");
} else if (bytesRead == 0) {
NSLog(@"No buffer received");
} else {
[receivedData appendBytes:buf length:bytesRead];
BOOL parserResult = [xmlParser parse];
if (parserResult == NO) {
NSLog(@"Unable to parse XML");
}
}
}
break;
}
default:
break;
}
}
@end
推荐答案
我想出了问题是什么，并回答这里的任何人遇到这个问题在未来，因为 + [NSXMLParser initWithStream]
I figured out what the problem was and answering it here incase anyone else runs into this problem in the future since +[NSXMLParser initWithStream] doesn't have a lot lot of documentation out there.
我需要调用 - [NSXMLParser parse] 我分配 NSXMLParser 并将自己设置为委托。但是因为它是一个同步函数，我需要调用它另一个线程，所以我不阻塞当前线程，它可以接收 NSStream 事件。我也不需要让自己成为 NSInputStream 的委托。
I needed to call -[NSXMLParser parse] right after I allocate NSXMLParser and set myself as delegate. But because it's a synchronous function, I need to call it another thread so I don't block the current thread and it can receive the NSStream events. I also don't need to make myself the delegate for NSInputStream.
这可以很简单地使用Grand中央调度（GCD）如下：
This can be done pretty simply using Grand Central Dispatch (GCD) like so:
// alloc and init the xml parser
xmlParser = [[NSXMLParser alloc] initWithStream:inputStream];
[xmlParser setDelegate:self];
// block to execute
dispatch_block_t dispatch_block = ^(void)
{
[xmlParser parse];
};
// create a queue with a unique name
dispatch_queue_t dispatch_queue = dispatch_queue_create("parser.queue", NULL);
// dispatch queue
dispatch_async(dispatch_queue, dispatch_block);
// cleanup
dispatch_release(dispatch_queue);
这里是完整的工作示例，只是因为任何人都无法跟上我发布的。
And here is the complete working example, just incase anyone wasn't able to follow what I posted above.
ContentParser.h
@interface ContentParser : NSObject <NSStreamDelegate,
NSXMLParserDelegate>
{
NSInputStream *inputStream;
NSOutputStream *outputStream;
NSMutableData *receivedData;
NSXMLParser *xmlParser;
}
- (void)initStream;
ContentParser.m
@implementation ContentParser
- (void)initStream
{
CFReadStreamRef readStream;
CFWriteStreamRef writeStream;
CFStreamCreatePairWithSocketToHost(kCFAllocatorDefault,
(CFStringRef)@"<hostname>",
<port>,
&readStream,
&writeStream);
inputStream = (__bridge NSInputStream *)readStream;
outputStream = (__bridge NSOutputStream *)writeStream;
outputStream.delegate = self;
[inputStream scheduleInRunLoop:[NSRunLoop currentRunLoop]
forMode:NSDefaultRunLoopMode];
[outputStream scheduleInRunLoop:[NSRunLoop currentRunLoop]
forMode:NSDefaultRunLoopMode];
[inputStream open];
[outputStream open];
xmlParser = [[NSXMLParser alloc] initWithStream:inputStream];
[xmlParser setDelegate:self];
dispatch_block_t dispatch_block = ^(void)
{
[xmlParser parse];
};
dispatch_queue_t dispatch_queue = dispatch_queue_create("parser.queue", NULL);
dispatch_async(dispatch_queue, dispatch_block);
dispatch_release(dispatch_queue);
}
- (void)parser:(NSXMLParser *)parser didStartElement:(NSString *)elementName
namespaceURI:(NSString *)namespaceURI
qualifiedName:(NSString *)qName
attributes:(NSDictionary *)attributeDict
{
dispatch_block_t dispatch_block = ^(void)
{
NSLog(@"didStartElement: %@, attributeDict: %@",
elementName, attributeDict);
};
dispatch_queue_t main_queue = dispatch_get_main_queue();
dispatch_async(main_queue, dispatch_block);
}
- (void)parser:(NSXMLParser *)parser foundCharacters:(NSString *)string
{
dispatch_block_t dispatch_block = ^(void)
{
NSLog(@"foundCharacters: %@", string);
};
dispatch_queue_t main_queue = dispatch_get_main_queue();
dispatch_async(main_queue, dispatch_block);
}
- (void)parser:(NSXMLParser *)parser didEndElement:(NSString *)elementName
namespaceURI:(NSString *)namespaceURI
qualifiedName:(NSString *)qName
{
dispatch_block_t dispatch_block = ^(void)
{
NSLog(@"didEndElement: %@", elementName);
};
dispatch_queue_t main_queue = dispatch_get_main_queue();
dispatch_async(main_queue, dispatch_block);
}
- (void)parser:(NSXMLParser *)parser parseErrorOccurred:(NSError *)parseError
{
dispatch_block_t dispatch_block = ^(void)
{
NSLog(@"Error %ld, Description: %@, Line: %ld, Column: %ld",
[parseError code], [[parser parserError] localizedDescription],
[parser lineNumber], [parser columnNumber]);
};
dispatch_queue_t main_queue = dispatch_get_main_queue();
dispatch_async(main_queue, dispatch_block);
}
- (void)stream:(NSStream *)stream handleEvent:(NSStreamEvent)eventCode
{
switch (eventCode) {
case NSStreamEventHasSpaceAvailable:
{
/* write bytes to socket */
break;
}
default:
break;
}
}
@end
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