导航控制器的 alpha 将重置 ？当应用从后台变为活动状态时

Question

1. 我在 AUIController 中，导航控制器.导航栏.alpha == 0.500
2. 我按下了主页按钮。
3. 我点击了appIcon回到AUIController。 导航控制器.导航栏.alpha 到 1.000

我该怎么做才能保持导航控制器.导航栏的 alpha = 0.5000 ;

我试过..

AUIController : UIViewController  <...,UINavigationControllerDelegate>
- (void) navigationController:(UINavigationController *)navigationController willShowViewController:(UIViewController *)viewController animated:(BOOL)animated {
    if (viewController == self) {
            //NSLog(@"self");
        //self.navigationController.navigationBar.tintColor = [UIColor colorWithRed:0.000 green:0.000 blue:0.000 alpha:1.000];
            self.navigationController.navigationBar.alpha = 0.500;
            self.navigationController.navigationBar.translucent = YES;
        } else {
            self.navigationController.navigationBar.alpha = 1.000;
            self.navigationController.navigationBar.translucent = NO;
        }
    }

但是当应用程序变得活跃时，alpha 0.50 变为 1.00将不调用显示视图控制器

Answer 1

您可以使用 KVO 来执行此操作。viewDidLoad AUIController添加此代码[self.navigationController.navigationBar addObserver:self forKeyPath:@"alpha" options:NSKeyValueObservingOptionNew | NSKeyValueObservingOptionOld context:(__bridge void *)(self)];

并实现此功能：

-(void)observeValueForKeyPath:(NSString *)keyPath ofObject:(id)object change:(NSDictionary *)change context:(void *)context
{
    NSLog([change description]);
    UIViewController *viewController = (__bridge UIViewController*)context;
    if ([viewController isKindOfClass:[AUIViewController class]]) {
        if (self.navigationController.navigationBar.alpha == 1) {
            self.navigationController.navigationBar.alpha = 0.500;
            self.navigationController.navigationBar.translucent = YES;
        }
    }
}

Answer 2

- (void)navigationController:(UINavigationController *)navigationController willShowViewController:(UIViewController *)viewController animated:(BOOL)animated
{
    self.navigationBar.translucent = NO;
    [self.navigationController.layer removeFromSuperlayer];
}
- (void)navigationController:(UINavigationController *)navigationController didShowViewController:(UIViewController *)viewController animated:(BOOL)animated
{
    self.navigationBar.translucent = YES;
}

Answer 3

只需在方法中写下以下代码

AppDelegate.m 文件。

- (void)applicationWillEnterForeground:(UIApplication *)application
 { 
    int count=self.navigationController.viewControllers.count;
    if([[[self.navigationController viewControllers] objectAtIndex:count-1] isKindOfClass:[AUIController Class]])
    {
        self.navigationController.navigationBar.alpha = 0.500;
        self.navigationController.navigationBar.translucent = YES;
    }
   else
    {
      self.navigationController.navigationBar.alpha = 1.000;
      self.navigationController.navigationBar.translucent = NO;
    }
}

我希望这对你有帮助。