举例说明怎么简单的创建一个子线程

用到的类是NSThread类，这里使用detachNewTheadSelector:toTagaet:withObject创建一个线程。

函数setupThread:(NSArray*)userInfor。通过userInfor将需要的数据传到线程中。

函数定义：

-(void)setupThread:(NSArray*)userInfor{

  
[NSThread detachNewThreadSelector:@selector(threadFunc:)
toTarget:self withObject:(id)userInfor];

}

- (void)threadFunc:(id)userInfor{

   NSAutoreleasePool*pool
= [[NSAutoreleasePool alloc]
init];

   //。。。。需要做的处理。

  
//这里线程结束后立即返回

  [self
performSelectorOnMainThread:@selector(endThread) withObject:nil
waitUntilDone:NO];

  [pool
release];

}

performSelectorOnMainThread通知主线程执行函数endThread。也可以使用performSelector:onThread:withObject:waitUntil
通知某线程执行线程结束后的处理。

线程内不要刷新界面。如果需要刷新界面，通过performSelectorOnMainThread，调出主线程中的方法去刷新。

 

例如，启动一个线程下载图片：

//启动线程

[NSThread
detachNewThreadSelector:@selector(downloadImage:) toTarget:self
withObject:url];

//线程函数

- (void) downloadImage:(NSString*)url{

    

    _subThreed =
[NSThread currentThread];

    

   
self.uploadPool = [[NSAutoreleasePool alloc]
init];

   
self.characterBuffer = [NSMutableData data];

    done =
NO;

    [[NSURLCache
sharedURLCache] removeAllCachedResponses];

    

   
NSMutableURLRequest *theRequest = [NSMutableURLRequest requestWithURL:[NSURLURLWithString:url]];

    

   
self.connection = [[NSURLConnection alloc]
initWithRequest:theRequest delegate:self];

    [self
performSelectorOnMainThread:@selector(httpConnectStart)
withObject:nil waitUntilDone:NO];

    if
(connection != nil) {

       
do {

           
[[NSRunLoop currentRunLoop] runMode:NSDefaultRunLoopMode
beforeDate:[NSDate distantFuture]];

       
} while (!done);

    }

    

    self.photo =
[UIImage imageWithData:characterBuffer];

    

   
//下载结束，刷新

    [self
performSelectorOnMainThread:@selector(fillPhoto) withObject:nil
waitUntilDone:NO];

    
   
// Release resources used only in this thread.

   
self.connection = nil;

    [uploadPool
release];

   
self.uploadPool = nil;

    

    _subThreed =
nil;

}

#pragma mark NSURLConnection Delegate
methods

/*

 Disable caching so that each time we run this app
we are starting with a clean slate. You may not want to do this in
your application.

 */

- (NSCachedURLResponse *)connection:(NSURLConnection *)connection
willCacheResponse:(NSCachedURLResponse *)cachedResponse {

    return
nil;

}

// Forward errors to the
delegate.

- (void)connection:(NSURLConnection *)connection
didFailWithError:(NSError *)error {

    done =
YES;

    [self
performSelectorOnMainThread:@selector(httpConnectEnd)
withObject:nil waitUntilDone:NO];

   
[characterBuffer setLength:0];

    

}

// Called when a chunk of data
has been downloaded.

- (void)connection:(NSURLConnection *)connection
didReceiveData:(NSData *)data {
   
// Process the downloaded chunk of data.

 

   
[characterBuffer appendData:data];

    

}

- (void)connectionDidFinishLoading:(NSURLConnection *)connection
{

    

    [self
performSelectorOnMainThread:@selector(httpConnectEnd)
withObject:nil waitUntilDone:NO];
   
// Set the condition which ends the run loop.

    done =
YES; 

}