UIScrollView setNeedsDisplay无法正常工作，还是其他什么？

时间：2012-02-07 18:17:08

标签： objective-c asynchronous uiscrollview uiimageview setneedsdisplay

问题的最终解决方案在

下面给出

我的目标是创建一个最初在滚动视图内创建每个图像视图的图像选择器，然后将该图像视图的引用传递给一个方法，该方法将使用适当的图像异步更新imageview.image 的

这样效果很好。

我遇到的问题是滚动视图仅在方法结尾处显示批处理中的图像视图，而我希望它们逐个打印，因为它们是创建（图像是否可用）。

如果我触摸滚动视图滚动，它会按照我想要的方式工作，但如果我完全没有触摸，屏幕会一直保持白色直到所有图像，而不仅仅是图像观点，已经完成加载。

我已尝试在每个视图中放置setNeedsDisplay，包括self.view，scrollview和每个单独的imageview。发生了什么事？

- (void)viewDidLoad {
     dispatch_queue_t queue = dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_HIGH, 0ul);
     dispatch_async(queue, ^{
          [self setGridView];
     });
}

- (void)setGridView {
    // begin loading images
    NSString * retina = ([[MVProject sharedInstance] settings_retina]) ? @"2" : @"";

    CGRect scrollframe = CGRectMake(0, 0, 300, 275);
    UIScrollView * newscrollview;
    newscrollview = [[UIScrollView alloc] initWithFrame:scrollframe];
    newscrollview.scrollEnabled = YES;
    newscrollview.delegate = self;
    [newscrollview setContentSize:CGSizeMake(300, (((ceilf([[NSKeyedUnarchiver unarchiveObjectWithData:[[NSUserDefaults standardUserDefaults] objectForKey:@"Flickr_Dictionary"]] count]/4)) * (58+15)) + 15 + 58 + 15))];
    [picsMVContentCell.contentView addSubview:newscrollview];

    float currentx = 11;
    float currenty = 17;
    NSInteger index = 0;

    for (NSDictionary * d in [NSKeyedUnarchiver unarchiveObjectWithData:[[NSUserDefaults standardUserDefaults] objectForKey:@"Flickr_Dictionary"]]) {

        // create button
        UIButton * button = [UIButton buttonWithType:UIButtonTypeCustom];
        button.frame = CGRectMake(currentx, currenty, 58, 58);
        button.imageView.backgroundColor = [UIColor colorWithRed:(241/255.0) green:(241/255.0) blue:(241/255.0) alpha:1];
        button.imageView.contentMode = UIViewContentModeScaleAspectFit;
        button.imageView.layer.cornerRadius = 6;
        button.imageView.layer.masksToBounds = YES;
        button.imageView.accessibilityLabel = [d objectForKey:@"id"];
        button.imageView.accessibilityValue = [d objectForKey:@"full"];
        button.imageView.tag = index++;
        [button addTarget:self action:@selector(imageClick:) forControlEvents:UIControlEventTouchUpInside];

        UIImage * image = [MVImage imageWithImage:[UIImage imageNamed:@""] covertToWidth:58.0f covertToHeight:58.0f];
        [button setImage:image forState:UIControlStateNormal];

        [newscrollview addSubview:button];
        [newscrollview bringSubviewToFront:button];
        [newscrollview setNeedsDisplay];

        // calculate next image view position
        currentx += (button.imageView.frame.size.width+15);
        if (currentx >= 289) {
            currentx = 11;
            currenty += (button.imageView.frame.size.height+15);
        }

        // set image
        NSString * nsuserdefault = [NSString stringWithFormat:@"Settings_SFThumbs%@_%@", retina, [d objectForKey:@"id"]];
        if ([NSKeyedUnarchiver unarchiveObjectWithData:[[NSUserDefaults standardUserDefaults] objectForKey:nsuserdefault]]) {
            MVImage * thumb = [NSKeyedUnarchiver unarchiveObjectWithData:[[NSUserDefaults standardUserDefaults] objectForKey:nsuserdefault]];
            [button setImage:[MVImage imageWithImage:[[UIImage alloc] initWithData:thumb.data] covertToWidth:58.0f covertToHeight:58.0f] forState:UIControlStateNormal];
        } else {
            [MVProject asynchronousImageLoad:button.imageView urlpath:[d objectForKey:@"thumb"] nsuserdefaultpath:nsuserdefault];
        }
    }
}

编辑于2012年2月7日下午3:26

这些更改修复了与问题中给出的代码相关的所有问题

感谢@Eugene指出我正确的方向

/* ---------- ---------- ---------- ---------- ---------- */

- (void)viewDidLoad {
     [super viewDidLoad];

     [[MVProject sharedInstance] syncLoadSF:0];

    self.newscrollview = [[UIScrollView alloc] initWithFrame:CGRectMake(0, 0, 300, 275)];
    self.newscrollview.scrollEnabled = YES;
    self.newscrollview.delegate = self;
    [self.newscrollview setContentSize:CGSizeMake(300, (((ceilf(([[NSKeyedUnarchiver unarchiveObjectWithData:[[NSUserDefaults standardUserDefaults] objectForKey:@"Flickr_Dictionary"]] count]-1)/4)) * (58+15)) + 15 + 58 + 15))];
    [picsMVContentCell.contentView addSubview:self.newscrollview];

    [self setGridView];
}

/* ---------- ---------- ---------- ---------- ---------- */

- (void)setGridView {
    NSString * retina = ([[MVProject sharedInstance] settings_retina]) ? @"2" : @"";
    [self.newscrollview setNeedsDisplay];
    dispatch_queue_t queue = dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_HIGH, 0ul);
    dispatch_async(queue, ^{
        NSInteger index = 0;
        for (NSDictionary * d in [NSKeyedUnarchiver unarchiveObjectWithData:[[NSUserDefaults standardUserDefaults] objectForKey:@"Flickr_Dictionary"]]) {
            // create button
            UIButton * button = [UIButton buttonWithType:UIButtonTypeCustom];               
            button.frame = CGRectMake((11 + ((index%4)*(58+15))), (17 + ((floorf(index/4))*(58+15))), 58, 58);
            button.imageView.backgroundColor = [UIColor colorWithRed:(241/255.0) green:(241/255.0) blue:(241/255.0) alpha:1];
            button.imageView.contentMode = UIViewContentModeScaleAspectFit;
            button.imageView.layer.cornerRadius = 3;
            button.imageView.layer.masksToBounds = YES;
            button.imageView.accessibilityLabel = [d objectForKey:@"id"];
            button.imageView.accessibilityValue = [d objectForKey:@"full"];
            button.imageView.tag = index++;
            [button addTarget:self action:@selector(imageClick:) forControlEvents:UIControlEventTouchUpInside];

            dispatch_sync(dispatch_get_main_queue(), ^ {
                [button setImage:[MVImage imageWithImage:[UIImage imageNamed:@""] covertToWidth:58.0f covertToHeight:58.0f] forState:UIControlStateNormal];
                [self.newscrollview addSubview:button];
                [self.newscrollview bringSubviewToFront:button];
                [self.newscrollview setNeedsDisplay];

                // set image
                NSString * nsuserdefault = [NSString stringWithFormat:@"Settings_SFThumbs%@_%@", retina, [d objectForKey:@"id"]];
                if ([NSKeyedUnarchiver unarchiveObjectWithData:[[NSUserDefaults standardUserDefaults] objectForKey:nsuserdefault]]) {
                    MVImage * thumb = [NSKeyedUnarchiver unarchiveObjectWithData:[[NSUserDefaults standardUserDefaults] objectForKey:nsuserdefault]];
                    [button setImage:[MVImage imageWithImage:[[UIImage alloc] initWithData:thumb.data] covertToWidth:58.0f covertToHeight:58.0f] forState:UIControlStateNormal];
                } else {
                    [MVProject asynchronousImageLoad:button.imageView urlpath:[d objectForKey:@"thumb"] nsuserdefaultpath:nsuserdefault];
                }
            });
        }
    });
    [self.newscrollview setNeedsDisplay];
}

2 个答案:

答案 0 :(得分：2)

您无法使用后台线程上的绘图。每次添加子视图时，都应该在主线程中执行此操作。所以你的救赎就是在同步块中使用你的绘图代码，它在主队列上运行

  dispatch_sync(dispatch_get_main_queue(), ^ {
    [newscrollview addSubview:button];
    [newscrollview bringSubviewToFront:button];
    [newscrollview setNeedsDisplay];

    // calculate next image view position
    currentx += (button.imageView.frame.size.width+15);
    if (currentx >= 289) {
      currentx = 11;
      currenty += (button.imageView.frame.size.height+15);
    }

    // set image
    NSString * nsuserdefault = [NSString stringWithFormat:@"Settings_SFThumbs%@_%@", retina, [d objectForKey:@"id"]];
    if ([NSKeyedUnarchiver unarchiveObjectWithData:[[NSUserDefaults standardUserDefaults] objectForKey:nsuserdefault]]) {
      MVImage * thumb = [NSKeyedUnarchiver unarchiveObjectWithData:[[NSUserDefaults standardUserDefaults] objectForKey:nsuserdefault]];
      [button setImage:[MVImage imageWithImage:[[UIImage alloc] initWithData:thumb.data] covertToWidth:58.0f covertToHeight:58.0f] forState:UIControlStateNormal];
    } else {
      [MVProject asynchronousImageLoad:button.imageView urlpath:[d objectForKey:@"thumb"] nsuserdefaultpath:nsuserdefault];
    }
  });

答案 1 :(得分：0)

您遇到的问题是设置图像。您尝试做的是将所有图像容器添加到scrollview。然后，当图像准备就绪，将它们装入容器中。有两种方法可以做到这一点。

首先将所有容器添加到scrollview。 （您可能需要一些加载指示器或默认图像来显示其加载）

1）创建后台线程以准备好图像。图像准备好后，将其添加到容器中。 （我发现这种方式更多的工作，有点痛苦）

2）创建一个自定义容器，让自定义容器在其映像就绪时添加自己的映像。

例如，我正在从服务器加载图像。所以我创建了AsyncImage类，它是UIImageView的自定义类。我创建了一个函数，我将图像url发送给它并处理剩下的部分。它创建一个NSURLConnection，并在加载数据时调用self.image = [UIImage imageWithData:data];

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