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我一开始就为这个冗长的问题道歉。

在我的应用程序中，我下载了大视频文件 (30-60Mb)。我显然想告诉用户进度。下载来自 Urban Airship，我使用他们的一种方法来获取进度。然而，这发生在 TableViewController 中，但下载指示器 (MBProgressHUD) 从另一个视图开始，称为 UADetail。

为了将进度从一个视图传递到另一个视图，我使用了 Singleton。随机地，它可能发生得早、晚或根本不发生，应用程序在日志中崩溃；

2012-03-12 15:13:30.528 isengua-en[3478:681f] HUD 课程下载进度：0.053478 2012-03-12 15:13:30.553 isengua-en[3478:707] 课程进度：0.055272 2012-03-12 15 :13:30.562 isengua-en[3478:707] LLVC downHUD 进度：0.055272 2012-03-12 15:13:30.565 isengua-en[3478:707] -[LessonListViewController >productsDownloadProgress:count:] [第 57 行] [StoreFrontDelegate ] productsDownloadProgress: 0.055272 count: 1 2012-03-12 15:13:30.569 isengua-en[3478:6307] * -[CFNumber _getValue:forType:]: 消息发送到解除分配的实例 0x83c6e80

首先是LessonListViewController；

- (void)productsDownloadProgress:(float)progress count:(int)count 
{
    DataManager *sharedManager = [DataManager sharedManager];
    sharedManager.downHUD = [NSNumber numberWithFloat:progress];
    NSLog(@"Lessonlist progress: %f", progress);
    NSLog(@"LLVC downHUD progress: %f", [sharedManager.downHUD floatValue]);
    UALOG(@"[StoreFrontDelegate] productsDownloadProgress: %f count: %d", progress, count);
    if (count == 0) {
        NSLog(@"Downloads complete in LessonListView!");
    }

}

单例看起来像这样；

@implementation DataManager

@synthesize downHUD;




+ (DataManager *)sharedManager
{
    static DataManager *sharedManager = nil;
    static dispatch_once_t predicate;
    dispatch_once(&predicate, ^{
        sharedManager = [[self alloc] init]; 
    });
    return sharedManager;

}

- (id)init {
    if (self = [super init]) {
        downHUD = [NSNumber numberWithFloat:(float)0];
    }
    return self;
}


 - (void)dealloc {
 // Should never be called, but just here for clarity really.
     NSLog(@"dealloc called in DataManager");
 }



@end

然后在 UADetail 中读取它；

- (void)showWithLabelDeterminate {

    HUD = [[MBProgressHUD alloc] initWithView:self.view]; 
    [self.view addSubview:HUD];


    // Set determinate mode
    HUD.mode = MBProgressHUDModeIndeterminate;
    HUD.delegate = self;
    HUD.labelText = NSLocalizedString(@"Waiting","");

    // myProgressTask uses the HUD instance to update progress
    [HUD showWhileExecuting:@selector(lessonDownloadProgress) onTarget:self withObject:nil animated:YES];
}


-(void)lessonDownloadProgress
{
    DataManager *sharedManager = [DataManager sharedManager];
    HUD.mode = MBProgressHUDModeDeterminate;
    HUD.progress = [sharedManager.downHUD floatValue];
    HUD.labelText = NSLocalizedString(@"DownLoading","");

    while (HUD.progress < 1)
    {
        [self parentViewController];
        NSLog(@"HUD lessonDownloadProgress: %f", HUD.progress);
        HUD.progress = [sharedManager.downHUD floatValue];                       
        NSString *percent = [NSString stringWithFormat:@"%.0f", HUD.progress/1*100];
        HUD.detailsLabelText = [percent stringByAppendingString:@"%"];
    }
}
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1 回答 1

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我想我自己找到了解决方案。在 while 循环中放入 usleep(50000) 后，它停止了。也许循环运行得太快并且过于频繁地检查 sharedManager.downHUD，从而干扰了其他类对其的写入。

于 2012-03-14T10:20:33.023 回答