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自定义UITableViewCell imageView在setImage之后未更新

uiimage uiimageview interface-builder uitableview iphone

Steve N · 技术社区 · 14 年前

我有一个定制的UITableViewCell类,它的模型对象执行异步下载要在单元格中显示的图像。我知道我已经在IB中为widgetvc正确连接了出口,我知道图像数据正在从我的服务器正确返回,并且我已经分配了小部件.logo你的形象也一样。为什么我的tableViewCell中的图像总是空白?提前谢谢。

- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath {

    Widget *theWidget = [widgetArray objectAtIndex:indexPath.row];

    static NSString *CellIdentifier = @"WidgetCell";
    WidgetTVC *cell = (WidgetTVC*)[self.tableView dequeueReusableCellWithIdentifier:CellIdentifier];

    if(cell == nil)
    {
        [[NSBundle mainBundle] loadNibNamed:@"WidgetTVC" owner:self options:nil];
        cell = self.widgetTVC;
        self.widgetTVC = nil;
    }

    [cell configureWithWidget:theWidget];

    return cell;
}

在我的WidgetTVC类中,我有以下方法:

- (void)configureWithWidget:(Widget*)aWidget {
    self.widget = aWidget;
    self.nameLbl.text = aWidget.name;
    [self.logoIvw setImage:aWidget.logo]; // logoIvw is the image view for the logo
}

最后,我得到了一个回调方法,它异步(简化)设置小部件模型对象的logo UIImage属性:

 (void)didReceiveImage:(ASIHTTPRequest *)request {
    // I pass a ref to the Widget's logo UIImage in the userInfo dict
    UIImage *anImage = (UIImage*)[request.userInfo objectForKey:@"image"];      
    UIImage *newImage = [UIImage imageWithData:[request responseData]];
    anImage = newImage;
 }

3 回复 | 直到 14 年前

bosmacs 14 年前

在 didReceiveImage: ,仅修改本地指针 anImage image UIImageView 以更新显示的内容。而不是隐藏对小部件的 UIImage UIImageView视图 ,和 接收图像: 像这样做

UIImageView *imageView = (UIImageView*)[request.userInfo objectForKey:@"imageView"]; 
UIImage *newImage = [UIImage imageWithData:[request responseData]];
imageView.image = newImage;

Ed Marty 14 年前

也许最好的解决方案是让模型对象将图像作为属性,而显示对象通过KVO订阅图像属性的更改,并在图像属性更改时更新自身。

Steve N 14 年前

首先,我向Widget对象添加了一个异步获取徽标的方法:

- (void)asyncImageLoad {
    ...
    // logo is a UIImage
    [AsyncImageFetch fetchImage:&logo fromURL:url];
}

+ (void)fetchImage:(UIImage**)anImagePtr fromURL:(NSURL*)aUrl {     
    ASIHTTPRequest *imageRequest = [ASIHTTPRequest requestWithURL:aUrl];    
    imageRequest.userInfo = [NSDictionary dictionaryWithObject:[NSValue valueWithPointer:anImagePtr] forKey:@"imagePtr"];
    imageRequest.delegate = self;
    [imageRequest setDidFinishSelector:@selector(didReceiveImage:)];
    [imageRequest setDidFailSelector:@selector(didNotReceiveImage:)];
    [imageRequest startAsynchronous];
}

+ (void)didReceiveImage:(ASIHTTPRequest *)request {
    UIImage **anImagePtr = [(NSValue*)[request.userInfo objectForKey:@"imagePtr"] pointerValue];    
    UIImage *newImage = [[UIImage imageWithData:[request responseData]] retain];
    *anImagePtr = newImage;
}

最后,根据Ed,我将此添加到帮助设置WidgetVC的configureWithWidget方法中:

[aCoupon addObserver:self forKeyPath:@"logo" options:0 context:nil];