NSURLConnection在NSOperation

Question

我正在写一个代码，它从http连接读取数据并存储在一个字节数组中。 我写了我自己的NSOperation类。代码的参考是

Concurrent Operations Demystified

我HttpWorker类的声明就像

@interface HttpWorker : NSOperation{ 

    NSString *param; 
    double requestCode; 
    BOOL isLive; 
    long initSleep; 
    BOOL _isFinished; 
    BOOL _isExecuting; 
    NSURL *_url; 
    NSURLConnection *_connection; 
    NSData *_data; 


} 

@property (nonatomic, retain) NSString *param; 
@property (nonatomic) double requestCode; 
@property (nonatomic) BOOL isLive; 
@property (nonatomic) long initSleep; 
@property (readonly) BOOL isFinished; 
@property (readonly) BOOL isExecuting; 
@property (readonly, copy) NSURL *url; 
@property (nonatomic, retain) NSURLConnection *httpCon; 
@property (readonly, retain) NSData *data; 



-(id)initWithUrl:(NSURL *)_url; 
-(void) setRequestParameters:(NSString *)parameters iRequestCode:(double)iRequestCode initialSleep:(long)initialSleep; 

@end 

而且我HttpWorker.m类就像

#import "HttpWorker.h" 
#import "Resources.h" 


@implementation HttpWorker 

@synthesize param; 
@synthesize requestCode; 
@synthesize isLive; 
@synthesize initSleep; 
@synthesize isFinished = _isFinished; 
@synthesize isExecuting = _isExecuting; 
@synthesize url = _url; 
@synthesize data = _data; 


-(id) initWithUrl: (NSURL *)Url{ 
    self = [super init]; 
    if(self == nil){ 
     return nil; 
    } 
    _url = [Url copy]; 
    _isExecuting = NO; 
    _isFinished = NO; 
    return self; 
} 

-(BOOL) isConcurrent{ 
    return YES; 
} 

-(void) start{ 
    if(![NSThread isMainThread]){ 
     [self performSelectorOnMainThread:@selector(start) withObject:nil waitUntilDone:NO]; 
     return; 
    } 
    [self willChangeValueForKey:@"isExecuting"]; 
    _isExecuting = YES; 
    [self didChangeValueForKey:@"isExecuting"]; 
    NSMutableURLRequest *request = [[NSMutableURLRequest alloc] initWithURL:_url]; 
    NSLog(@"Connecting... %@",_url); 
    _connection = [[NSURLConnection alloc] initWithRequest:request delegate:self startImmediately: YES]; 
    if(_connection == nil){ 
     NSLog(@"connection is nil"); 
    } 
} 


-(void) setRequestParameters:(NSString *)parameters iRequestCode:(double)iRequestCode initialSleep:(long)initialSleep { 
    self.param = parameters; 
    self.requestCode = iRequestCode; 
    self.initSleep = initialSleep; 
} 

/////////////////////////// delegate methods /////////////////////////////// 

-(void) connection:(NSURLConnection *)connection didReceiveResponse:(NSURLResponse *)response { 
    NSLog(@"receieved response..."); 
    _data = [[NSData alloc] init]; 
} 


-(void) connection:(NSURLConnection *)connection didReceiveData:(NSData *)incomingData { 
    NSLog(@"receieved data..."); 
} 


-(void) connectionDidFinishLoading:(NSURLConnection *) connection { 
    NSLog(@"connection did finish loading..."); 
} 


@end 

问题是，当我运行这段代码并将httpworker对象添加到NSOperationQueue中，代码将成功运行并且_connection不为零，但不会执行任何委托方法。任何人都可以帮忙吗？

感谢和问候......

Answer 1

您的连接委托是“自我”（=你的NSOperation对象）。我想这个对象在连接想要发送消息给委托时已经不存在了。

您的NSOperation没有“主要”实现。因此在线程启动后没有任何事情发生。它会（异步地）发动NSOperation并退出。

参见： http://developer.apple.com/mac/library/documentation/Cocoa/Reference/NSOperation_class/Reference/Reference.html#//apple_ref/occ/instm/NSOperation/main

---

底线：我强烈建议ASIHTTPRequest对于这样的任务。

http://allseeing-i.com/ASIHTTPRequest/