Question

我正在使用扫描蓝牙设备的方法，我从另一个框架导入。扫描方法需要一段时间，它会阻止GUI，这是我们从未想过的。

我也有MBProgressHud，试图在扫描时显示一个hud，但它没有工作（hud没有显示）。有什么帮助吗？

以下是我目前正在使用的代码：

    [hud showAnimated:YES whileExecutingBlock:^{
          self.btDevices = [Util scanBT];
    }];

编辑1：好的，所以如果我使用这段代码，它会暂时阻止我的用户界面，然后突然继续运行。

    hud = [[MBProgressHUD alloc] initWithView:self.view];
    hud.labelText = @"Now scanning";

    hud.dimBackground = YES;
    hud.opacity = 0.5;
    [hud show:YES];
    [hud hide:YES afterDelay:5.0];

    dispatch_after(dispatch_time(DISPATCH_TIME_NOW, 0.001 * NSEC_PER_SEC), dispatch_get_main_queue(), ^(void){
        self.btDevices = [Util scanBT];
    });

编辑2：好的，我将发布我的所有代码块：

    hud = [[MBProgressHUD alloc] initWithView:[self getTopView:self.view]];
    hud.labelText = @"Now scanning";

    hud.dimBackground = YES;
    hud.opacity = 0.5;

    [hud showAnimated:YES whileExecutingBlock:^{
          self.btDevices = [Util scanBT];
     }];

    dispatch_queue_t myqueue = dispatch_queue_create("queue", NULL);
    dispatch_async(myqueue, ^{

        //Whatever is happening in the BT scanning method will now happen in the background
        dispatch_async(dispatch_get_main_queue(), ^{

            [MBProgressHUD hideHUDForView:[self getTopView:self.view] animated:YES];
        });
    });

/** Recursion to get the top most view in view layer. */
- (UIView *)getTopView:(UIView *)view
{
    if ([view.superview class]) {
        return [self getTopView:view.superview];
    }

    return view;
}

我请求在弹出框中扫描bt，但是我想在主视图中显示HUD，所以我写了一个块来检索主视图。也许这就是问题发生的地方？

Answer 1

试试这个：

在viewDidload或您要放置它的方法

MBProgressHUD *hud = [[MBProgressHUD alloc] initWithView:self.view];
    [hud setDimBackground:YES];
    [hud setOpacity:0.5f];
    [hud show:YES];
    [hud hide:YES afterDelay:5.0];
 [self performSelector:@selector(startScanning) withObject:nil afterDelay:5.0];

和你的方法

- (void) startScanning {

    self.btDevices = [Util scanBT];
}

或者我认为你应该尝试运行

dispatch_after(dispatch_time(DISPATCH_TIME_NOW, 0.001 * NSEC_PER_SEC), dispatch_get_main_queue(), ^(void){
    // Insert task code here
self.btDevices = [Util scanBT];
});

尝试使用完成块

[hud showAnimated:YES whileExecutingBlock:^{
       self.btDevices = [Util scanBT];
    } completionBlock:^{
      //code for after completion 
    }];

或者你也可以试试这个

[MBProgressHUD showHUDAddedTo:self.view animated:YES];

dispatch_queue_t myqueue = dispatch_queue_create("queue", NULL);
dispatch_async(myqueue, ^{

    //Whatever is happening in the BT scanning method will now happen in the background
   self.btDevices = [Util scanBT];

    dispatch_async(dispatch_get_main_queue(), ^{

        [MBProgressHUD hideHUDForView:self.view animated:YES];
    });
});

MBProgressHUD showAnimated：whileExecutingBlock：not working

1 个答案: