ios - A issue on Changing the Color of the Status Bar when switching apps on iPhone

Question

I want to change the Status Bar color with the specific view controller.

According to StackOverFlow's answers , i achieved it.

There is an issue , when switching apps on iPhone, the color I have set fades, goes back to initial state.

It's OK. Please notice the status bar.

Not OK. Please notice the status bar.

I can't figure it out. The code I tried:

1. set statusBar.backgroundColor,

   UIView *statusBar = [[[UIApplication sharedApplication] valueForKey:@"statusBarWindow"] valueForKey:@"statusBar"];
   if ([statusBar respondsToSelector:@selector(setBackgroundColor:)]) {
        statusBar.backgroundColor = [UIColor redColor ];
   }
   

2. insert subview to statusBar.

 UIView *statusBar = [[[UIApplication sharedApplication] valueForKey:@"statusBarWindow"] valueForKey:@"statusBar"];
 UIView * backgroundColorView = [[UIView alloc] initWithFrame:CGRectMake(0, 0, 375, 20) ];
 backgroundColorView.autoresizingMask = UIViewAutoresizingFlexibleWidth;
 backgroundColorView.backgroundColor = [UIColor redColor ];
 [statusBar.subviews.firstObject insertSubview: backgroundColorView atIndex:0];

3. So is to insert layer(CALayer).

And I tried to analyze it with breakpoints.

- When the app is a active, and double-click the Home button to Switch apps, the method is not called - (void)viewWillDisappear:(BOOL)animated . It confuses me a little .

- I try to change the background color of status bar in the Application's method - (void)applicationWillResignActive:(UIApplication *)application, It doesn't work. I don't know why.

While from Github's source code, It's OK through Runtime. My company don't like using Runtime.

Is there some other way without runtime ?

And I don't know how runtime interacts with iPhone's switching apps mode.

The main question is to solve it without runtime. More explain is welcomed. i think it is easy , what do i miss ?

Many thanks in advances.

Answer 1

Answer for Swift 4:

And it fits the situation of viewControllers managed by navigationViewController

class ViewController: UIViewController {

    let statusBarBgView = { () -> UIView in
        let statusBarWindow: UIView = UIApplication.shared.value(forKey: "statusBarWindow") as! UIView
        let statusBarBgView = UIView(frame: (statusBarWindow.statusBar?.bounds)!)
        return statusBarBgView
    }()


    override func viewDidLoad() {
        super.viewDidLoad()
        // Do any additional setup after loading the view, typically from a nib.
    }

    override func viewWillAppear(_ animated: Bool) {
        super.viewWillAppear(animated)
        UIApplication.shared.statusBarStyle = .lightContent
        let navigationBar = self.navigationController?.navigationBar
        self.statusBarBgView.backgroundColor = UIColor.red
        navigationBar?.superview?.insertSubview(self.statusBarBgView, aboveSubview: navigationBar!)
    }


    override func viewWillDisappear(_ animated: Bool) {

        self.statusBarBgView.removeFromSuperview()
        super.viewWillDisappear(animated)
    }

}

extension UIView {
    var statusBar: UIView? {
        return value(forKey: "statusBar") as? UIView
    }
}

The Answer Of Objective-C version:

-(void)viewWillAppear:(BOOL)animated{
    [super viewWillAppear: animated];
    [UIApplication sharedApplication].statusBarStyle=UIStatusBarStyleLightContent;
    UINavigationBar *navigationBar = self.navigationController.navigationBar;
    UIView *statusBar = [[[UIApplication sharedApplication] valueForKey:@"statusBarWindow"] valueForKey:@"statusBar"];
    self.statusBarBgView = [[UIView alloc ] initWithFrame: statusBar.bounds ];
    self.statusBarBgView.backgroundColor = [UIColor redColor ];
    [navigationBar.superview insertSubview: self.statusBarBgView aboveSubview: navigationBar];
}

- (void)viewWillDisappear:(BOOL)animated {
    [self.statusBarBgView removeFromSuperview ];
    [super viewWillDisappear:animated];
}

The status bar which shows the OS infos，is UIWindow ,controlled by the OS when in the app switcher window.

UIView *statusBar = [[[UIApplication sharedApplication] 
valueForKey:@"statusBarWindow"] valueForKey:@"statusBar"];

So it's OK to adjust the background color of the status bar position by changing the View , when in the app switcher window.