Question

我使用NSOperationQueue加载UIImageView。

负载从Internet获取图像，然后将其添加到图像视图中。我遇到的问题是该方法完成但是大约需要3秒才能使图像视图实际显示图像或从超视图中删除图像视图......

- (void)viewDidLoad { NSLog(@"AirportDetailView: viewDidLoad");
    [super viewDidLoad];
    [self.activity startAnimating];
    self.queue = [NSOperationQueue new];
    NSInvocationOperation *operation = [[NSInvocationOperation alloc] initWithTarget:self selector:@selector(loadImage) object:NULL]; 
    [self.queue addOperation:operation]; 
    [operation release];
}

-(void)loadImage {
        [myAp ImageForAp];

        NSLog(@"ImageFor Ap Ended, %@",myAp.ApDiagram);

        [self.activity stopAnimating];

        if (myAp.ApDiagram==NULL) {
            NSLog(@"Finally Gets Here");
            [self.Diagram removeFromSuperview];
        }
        else {
            NSLog(@"Finally Gets Here with Diag");
            [self.Diagram setBackgroundImage:myAp.ApDiagram forState:UIControlStateNormal];
        }

    }

NSLOG显示前两个日志语句之间的延迟约3秒钟无法理解为什么......

更新了我的最新代码......

-(void)loadImage {

    [myAp ImageForAp];

    NSLog(@"ImageFor Ap Ended, %@",myAp.ApDiagram);

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

-(void)UpdateUI {

    [self.activity stopAnimating];

    if (myAp.ApDiagram==NULL) {
        NSLog(@"Finally Gets Here");
        [self.Diagram removeFromSuperview];
    }
    else {
        NSLog(@"Finally Gets Here with Diag");
        [self.Diagram setBackgroundImage:myAp.ApDiagram forState:UIControlStateNormal];
    }
}

Answer 1

确保在主线程上运行loadImage方法。所有UI操作都需要在主线程上发生才能按预期工作。您的代码需要与此类似。

-(void)loadImage {
    [myAp ImageForAp];
    [self performSelectorOnMainThread:@selector(UpdateUI) withObject:nil waitUntilDone:NO];
}

-(void)UpdateUI {
    [self.activity stopAnimating];

    if (myAp.ApDiagram==NULL) {
        [self.Diagram removeFromSuperview];
    }
    else {
        [self.Diagram setBackgroundImage:myAp.ApDiagram forState:UIControlStateNormal];
    }
}

viewDidLoad中也可能存在内存泄漏。

self.queue = [NSOperationQueue new];应更改为

self.queue = [[[NSOperationQueue alloc] init] autorelease];

通过OperationQueue加载UIImageView的问题

1 个答案: