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从不是主线程的线程更改gui?

multithreading cocoa-touch cocoa iphone

Shingoo · 技术社区 · 14 年前

我的想法是有一个视图,当一些东西是在幕后计算时,它会向用户显示。这是一个高度为30px的视图,包含一个uiActivityIndicatorView和一个uiLabel,显示当前正在计算的内容。

我试图通过使用以下方法使用activityhandler来实现它:

- (void)newActivityStarted{
    [self performSelectorOnMainThread:@selector(showActivityViewer) withObject:nil waitUntilDone:NO];
}

- (void)activityStopped{
    [self performSelectorOnMainThread:@selector(hideActivityViewer) withObject:nil waitUntilDone:NO];
}

- (void)changeInfoText:(NSString*)infoText{
    [activityView.infoLabel performSelectorOnMainThread:@selector(setText:) withObject:infoText waitUntilDone:NO];
}

以下是在主线程上调用的方法:

-(void)hideActivityViewer{
    CGContextRef context = UIGraphicsGetCurrentContext();
    [UIView beginAnimations:nil context:context];

    [UIView setAnimationCurve:UIViewAnimationCurveEaseOut];
    [UIView setAnimationDuration:0.2];
    [UIView setAnimationDelegate: self];
    [UIView setAnimationDidStopSelector:@selector(closeActivityViewer:finished:context:)];
    [activityView setFrame:CGRectMake(320, 10, 320, 30)];

    [UIView commitAnimations];
}

-(void)closeActivityViewer:(NSString*)id finished:(BOOL)finished context:(id)context{

    [activityView removeFromSuperview];
    [activityView release];
    activityView = nil;
}

-(void)showActivityViewer{

    activityView = [[BCActivityView alloc] initWithFrame:CGRectMake(320, 10, 320, 30)];
    [activityView.infoLabel setText:NSLocalizedString(@"WorkInProgressKey",nil)];

    [[(MyAppDelegate*)[[UIApplication sharedApplication] delegate] window] addSubview: activityView];

    CGContextRef context = UIGraphicsGetCurrentContext();
    [UIView beginAnimations:nil context:context];

    [UIView setAnimationCurve:UIViewAnimationCurveEaseIn];
    [UIView setAnimationDuration:0.2];
    [activityView setFrame:CGRectMake(0, 10, 320, 30)];

    [UIView commitAnimations];
}

newActivityStarted、activityStopped和changeInfoText方法由正在计算一些耗时数据的后台线程调用。

将按如下方式打开耗时的线程:

NSInvocationOperation* operation = [[NSInvocationOperation alloc] initWithTarget:self selector:@selector(calculateData) object:nil];
[[[NSOperationQueue new] autorelease] addOperation:operation];
[operation release];

计算过程如下:

-(void) calculateData{
    [[ActivityIndicatorHandler instance] newActivityStarted];
    [[ActivityIndicatorHandler instance] changeInfoText:NSLocalizedString(@"InitializingForecastKey", nil)];

    //Do something time consuming

    [[ActivityIndicatorHandler instance] activityStopped];
}

其效果是,在完成整个计算之后,显示并隐藏活动视图。我希望gui显示视图并负责用户交互,而计算是在后台完成的。但是,即使我在计算中有一个断点,在计算线程完成其工作以及活动视图未显示之前,该视图将不可用…我不知道怎么了…

有人知道吗?

3 回复 | 直到 14 年前

Chip Coons 14 年前

@implementation ActivityHandler;

//....
- (void)newActivityStarted{
    [self performSelectorOnMainThread:@selector(showActivityViewer) withObject:nil waitUntilDone:NO];
}

- (void)activityStopped{
    [self performSelectorOnMainThread:@selector(hideActivityViewer) withObject:nil waitUntilDone:NO];
}

- (void)changeInfoText:(NSString*)infoText{
    [activityView.infoLabel performSelectorOnMainThread:@selector(setText:) withObject:infoText waitUntilDone:NO];
}


- (NSInvocationOperation*)myOperation:
{
    NSInvocationOperation* operation = [[[NSInvocationOperation alloc] initWithTarget:self selector:@selector(calculateData) object:nil] autorelease];
    return operation;
}

在其他一些方法中,可能是应用程序委托,在初始值设定项中设置本地队列:

NSOperaionQueue* aQueue = [[[NSOperationQueue alloc] init] retain];  //release in dealloc
ActivityHandler* myHandler [[[ActivityHandler alloc] init] retain];  //release in dealloc

Have a method to add ops to the queue:

-(void)queueOperation:(NSInvocationOperation*)anOp;
{
    [aQueue addOperation:anOp];
}

-(IBAction*)startCalcs:(id)sender;
{
    [self queueOperation:[myHandler myOperation]];

}

Felix Lamouroux 14 年前

您是否尝试通过执行以下操作来调用计算:

[self performSelectorInBackground:@selector(calculateData) withObject:nil];

HiveHicks 14 年前

我想您需要考虑performselectornmainthread:withobject:waituntildone:method