NSOperation和NSNotificationCenter在主线

Question

我有一个NSOperation.当它完成我的防火一NSNotificationCenter让程序知道，NSoperation完成并更新界面。

我的的听众了解到NSNotification将不会运行的主线，因为NSOperation不是在主线。

我怎么能让这监听器上运行的主要线时，我的火我的事件吗？

[[NSNotificationCenter defaultCenter] postNotificationName:@"myEventName" object:self]; 

Answer 1

你可以使用 performSelectorOnMainThread:withObject:waitUntilDone: 与使用的辅助方法，在一个类似的方式对下面的例子。

.....
[self performSelectorOnMainThread:@selector(fireNotification) withObject:nil waitUntilDone:YES];
...

- (void)fireNotification {
  [[NSNotificationCenter defaultCenter] postNotificationName:@"myEventName" object:self]; 
}

如果你不要等到正在做，你会需要考虑的情况下，其他的线可以指的对象，这可能是已经清除以前的主线程中得到援引。

Answer 2

更新： 调度队列使张贴在主线程的通知很容易的。

dispatch_async(dispatch_get_main_queue(),^{
   [[NSNotificationCenter defaultCenter] postNotification...];
});

要等待通知处理程序到结束，只是dispatch_sync替换dispatch_async。

---

继notnoop的答案，这里的一些基础设施，您可以使用主线程的安全上发表您的通知，而不的等着他们完成。希望有人会发现这是很有帮助的！

NSNotificationCenter + Utils.h：

@interface NSNotificationCenter (Utils)

-(void)postNotificationOnMainThread:(NSNotification *)notification;
-(void)postNotificationNameOnMainThread:(NSString *)aName object:(id)anObject;
-(void)postNotificationNameOnMainThread:(NSString *)aName object:(id)anObject userInfo:(NSDictionary *)aUserInfo;

@end

NSNotificationCenter + Utils.m：

@interface NSNotificationCenter (Utils_Impl) {
}

-(void)postNotificationOnMainThreadImpl:(NSNotification*)notification;
-(void)postNotificationNameOnMainThreadImpl:(NSString *)aName object:(id)anObject userInfo:(NSDictionary *)aUserInfo;

@end

@implementation NSNotificationCenter (Utils)

-(void)postNotificationOnMainThread:(NSNotification *)notification {
    [notification retain];
    [notification.object retain];
    [self performSelectorOnMainThread:@selector(postNotificationOnMainThreadImpl:) 
                           withObject:notification
                        waitUntilDone:NO];
}

-(void)postNotificationNameOnMainThread:(NSString *)aName object:(id)anObject {
    [self postNotificationNameOnMainThread:aName object:anObject userInfo:nil];
}

-(void)postNotificationNameOnMainThread:(NSString *)aName object:(id)anObject userInfo:(NSDictionary *)aUserInfo {
    [aName retain];
    [anObject retain];
    [aUserInfo retain];

    SEL sel = @selector(postNotificationNameOnMainThreadImpl:object:userInfo:);
    NSMethodSignature* sig = [self methodSignatureForSelector:sel];
    NSInvocation* invocation = [NSInvocation invocationWithMethodSignature:sig];
    [invocation setTarget:self];
    [invocation setSelector:sel];
    [invocation setArgument:&aName atIndex:2];
    [invocation setArgument:&anObject atIndex:3];
    [invocation setArgument:&aUserInfo atIndex:4];
    [invocation invokeOnMainThreadWaitUntilDone:NO];
}

@end

@implementation NSNotificationCenter (Utils_Impl)

-(void)postNotificationOnMainThreadImpl:(NSNotification*)notification {
    [self postNotification:notification];
    [notification.object release];
    [notification release];
}

-(void)postNotificationNameOnMainThreadImpl:(NSString *)aName object:(id)anObject userInfo:(NSDictionary *)aUserInfo {
    [self postNotificationName:aName object:anObject userInfo:aUserInfo];
    [aName release];
    [anObject release];
    [aUserInfo release];
}

@end

NSInvocation的+ Utils.h：

@interface NSInvocation (Utils)

-(void)invokeOnMainThreadWaitUntilDone:(BOOL)wait;

@end

NSInvocation的+ Utils.m：

@implementation NSInvocation (Utils)

-(void)invokeOnMainThreadWaitUntilDone:(BOOL)wait
{
    [self performSelectorOnMainThread:@selector(invoke)
                           withObject:nil
                        waitUntilDone:wait];
}

@end

Answer 3

如果你在10.6，还可以使用 setCompletionBlock:.这是使用这样的：

NSOperation*op= .... ;
[op setCompletionBlock:^{
    dispatch_async(dispatch_get_main_queue(),^{
        code to be run on the main thread after the operation is finished.
    });
}];

对于一般的介绍块和GCD， 这篇文章 是非常有帮助的。我发现GCD&setCompletionBlock更易于读取比NSNotification.一个警告，那么，它只运行10.6!

Answer 4

这里

要扩大Danra的回答是我放在一起类别的ARC兼容的版本：

<强> NSNotificationCenter + Threads.h

@interface NSNotificationCenter (Threads)

-(void)postNotificationOnMainThread:(NSNotification *)notification;
-(void)postNotificationNameOnMainThread:(NSString *)name object:(id)object;
-(void)postNotificationNameOnMainThread:(NSString *)name object:(id)object userInfo:(NSDictionary *)userInfo;

@end

<强> NSNotificationCenter + Threads.m

@implementation NSNotificationCenter (Threads)

-(void)postNotificationOnMainThread:(NSNotification *)notification
{
    [self performSelectorOnMainThread:@selector(postNotification:) withObject:notification waitUntilDone:NO];
}

-(void)postNotificationNameOnMainThread:(NSString *)name object:(id)object
{
    [self postNotificationNameOnMainThread:name object:object userInfo:nil];
}

-(void)postNotificationNameOnMainThread:(NSString *)name object:(id)object userInfo:(NSDictionary *)userInfo
{
    dispatch_async(dispatch_get_main_queue(), ^{
        [self postNotificationName:name object:object userInfo:userInfo];
    });
}

@end