navigationController alpha会重置吗？当应用程序从后台激活时

Question

1. 我在AUIController中，navigationController.navigationBar.alpha == 0.500
2. 我按了主页按钮。
3. 我点击appIcon返回AUIController。 navigationController.navigationBar.alpha为1.000

如何保持navigationController.navigationBar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;
        }
    }

但是当应用程序变为活动状态时，alpha 0.50变为1.00 willShowViewController不能被调用

Answer 1

您可以使用KVO来做到这一点。在viewDidLoad的{​​{1}}中添加此代码AUIController

并实现此功能：

[self.navigationController.navigationBar addObserver:self forKeyPath:@"alpha" options:NSKeyValueObservingOptionNew | NSKeyValueObservingOptionOld context:(__bridge void *)(self)];

Answer 2

只需在方法

中记下以下代码即可

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;
    }
}

我希望这会对你有所帮助。

Answer 3

- (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;

}