iOS 图形界面刷新

Question

我在我的 GUI 上使用 setNeedsDisplay，但有时没有完成更新。我正在使用 UIPageControllView，每个页面都有 UIScrollView，里面有 UIView。

我有以下管道:

1) 应用程序来自后台 - 称为 applicationWillEnterForeground

2) 开始从服务器下载数据

2.1)数据下载完成后，触发selector

3) 使用 dispatch_async 和 dispatch_get_main_queue() 用新数据填充标签、图像等

3.1) 在 View 上调用setNeedsDisplay(也尝试在 ScrollView 和页面 Controller 上)

问题是，调用了步骤 3.1，但只是不时更改 apper。如果我交换页面，刷新完成并且我可以看到新数据(因此下载工作正常)。但是没有手动翻页，就没有更新。

有什么帮助吗？

编辑:步骤 3 和 3.1 中的代码(删除了注释中指向的 _needRefresh 变量)

 -(void)FillData {
    dispatch_async(dispatch_get_main_queue(), ^{

    NSString *stateID = [DataManager  ConvertStateToStringFromID:_activeCity.actual_weather.state];

    if ([_activeCity.actual_weather.is_night boolValue] == YES)
    {
          self.contentBgImage.image = [UIImage imageNamed:[NSString stringWithFormat:@"bg_%@_noc", [_bgs objectForKey:stateID]]];

        if (_isNight == NO)
        {
            _bgTransparencyInited = NO;
        }

        _isNight = YES;

    }
    else
    {
        self.contentBgImage.image = [UIImage imageNamed:[NSString stringWithFormat:@"bg_%@", [_bgs objectForKey:stateID]]];

        if (_isNight == YES)
        {
            _bgTransparencyInited = NO;
        }

        _isNight = NO;

    }
    [self.contentBgImage setNeedsDisplay]; //refresh background image

    [self CreateBackgroundTransparency]; //create transparent background if colors changed - only from time to time


    self.contentView.parentController = self;
    [self.contentView FillData]; //Fill UIView with data - set labels texts to new ones

    //_needRefresh is set to YES after application comes from background

    [self.contentView setNeedsDisplay]; //This do nothing ?

    [_grad display]; //refresh gradient

}); 
}

这里是数据下载后调用的选择器(在 MainViewController 中)

-(void)FinishDownload:(NSNotification *)notification
{
    dispatch_async(dispatch_get_main_queue(), ^{

        [_activeViewController FillData]; //call method shown before

        //try call some more refresh - also useless
        [self.pageControl setNeedsDisplay];

         //[self reloadInputViews];
         [self.view setNeedsDisplay];


    });

} 

在 AppDelegate 中，我有来自后台的应用程序:

-(void)applicationWillEnterForeground:(UIApplication *)application
{
    MainViewController *main = (MainViewController *)[(SWRevealViewController *)self.window.rootViewController frontViewController];


    [main UpdateData];
} 

在主视图 Controller 中

-(void)UpdateData
{

    [[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(FinishForecastDownload:) name:@"FinishDownload" object:nil]; //create selector

    [[DataManager SharedManager] DownloadForecastDataWithAfterSelector:@"FinishDownload"]; //trigger download
}

Answer 1

试试这个:

[self.view performSelectorOnMainThread:@selector(setNeedsLayout) withObject:nil waitUntilDone:NO];

或查看此链接:

http://blackpixel.com/blog/2013/11/performselectoronmainthread-vs-dispatch-async.html