Iphone 如何在所有视图的顶部添加UIView？

我有这样的代码：

@interface Alert : UIView 
{

}
/*
- (void) initWithTitle:(NSString*)title message:(NSString*)message cancelButtonTitle:(NSString*)cancelButtonTitle otherButtonTitles:(NSString*)buttonTitle,... delegate:(id)delegate;
*/
@end


@implementation Alert

- (void) drawRect:(CGRect)rect 
{
    CGContextRef context = UIGraphicsGetCurrentContext();
    CGContextClearRect(context, rect); // Очистим context

    CGContextSetRGBFillColor(context, 255, 0, 0, 1);
    CGContextFillRect(context, CGRectMake(20, 20, 100, 100));
}

- (void) show
{
    self.center = [[[UIApplication sharedApplication] keyWindow] center];
    [[[UIApplication sharedApplication] keyWindow] addSubview:self];
    [[[UIApplication sharedApplication] keyWindow] bringSubviewToFront:self];
}

那我就这样用它：

- (void)viewDidLoad
{
    [super viewDidLoad];
     Alert * alert = [[Alert alloc] initWithFrame:CGRectMake(0, 0, 100, 100)];
    [alert show];
    [alert release];
}

---

但它不起作用（我希望看到警报高于所有其他视图）。您能帮助我吗？

正确处理设备方向的推荐解决方案有

• 豆荚 它将自动处理任何旋转和帧更改，因此您不必担心这一点
• 阅读并遵循官方公告
• 将视图添加到第一个子视图，而不是将其添加到窗口
  

也可以将其添加到窗口中但它不会处理设备方向。

let window = UIApplication.sharedApplication().keyWindow!
let view = UIView(frame: CGRect(x: window.frame.origin.x, y: window.frame.origin.y, width: window.frame.width, height: window.frame.height))
window.addSubview(v);
view.backgroundColor = UIColor.blackColor()

---

如果知道顶部的子视图，请使用：

UIView* topMostSubView = <your view's top most subview>
[self.view insertSubview:alert aboveSubview:topMostSubView];

---

UIView*topMostSubView=还有一种方法

在视图中添加以下方法将在每次推/弹出视图控制器时显示为添加

-(void)viewWillAppear:(BOOL)animated
{
     [super viewWillAppear:animated];

     [[[UIApplication sharedApplication] keyWindow] addSubview:<yourViewObject>];
}

-（void）视图将显示：（BOOL）动画
{
[超级视图将显示：动画]；
[[[UIApplication sharedApplication]键窗口]添加子视图：]；
}

要在下一个类中删除此视图，请添加以下代码行

-(void)viewWillDisappear:(BOOL)animated
{
    [super viewWillDisappear:animated];

    [<yourViewObject> removeFromSuperview];
 }

-（void）视图将消失：（BOOL）动画
{
[超级视图将消失：动画]；
[removeFromSuperview]；
}
@MaciekWrocław answere swift版本

Swift2

 var appDelegate = (UIApplication.sharedApplication().delegate! as! AppDelegate)
 var backgrView = UIView(frame: CGRectMake(0, 0, UIScreen.mainScreen().bounds.size.width, UIScreen.mainScreen().bounds.size.height))
 backgrView.backgroundColor = UIColor.redColor()
 backgrView.alpha = 0.6
 window?.addSubview(backgrView)

swift3

     var appDelegate: AppDelegate? = (UIApplication.shared.delegate as? AppDelegate)
     var backgrView = UIView(frame: CGRect(x: CGFloat(0), y: CGFloat(0), width: CGFloat(UIScreen.main.bounds.size.width), height: CGFloat(UIScreen.main.bounds.size.height)))
     backgrView.backgroundColor = UIColor.red
     backgrView.alpha = 0.6
     window?.addSubview(backgrView)

我正在为我的应用程序在AppDelegate中执行有关网络连接的操作：

func checkReachabilityUpdateUI() -> Int {

    let remoteHostStatus = self.reachability?.currentReachabilityStatus()


    if remoteHostStatus?.rawValue == 0 {
        let backgrView = UIView(frame: CGRectMake(0, 60, UIScreen.mainScreen().bounds.size.width, 44))

        let statusMessage = UILabel(frame: CGRect(x: 0, y: 0, width: UIScreen.mainScreen().bounds.size.width, height: 44))

        statusMessage.text = "No internet Connection"
        statusMessage.textAlignment = .Center
        statusMessage.textColor =  UIColor.whiteColor()

        backgrView.backgroundColor = UIColor.redColor()

        backgrView.addSubview(statusMessage)

        backgrView.tag = 100

        window?.addSubview(backgrView)

        return (remoteHostStatus?.rawValue)!

    }
    else {

        if let viewWithTag = self.window!.viewWithTag(100) {
            print("Tag 100")
            viewWithTag.removeFromSuperview()
        }
        else {
            print("tag not found")
        }

       return (remoteHostStatus?.rawValue)!

    }

}

斯威夫特5

let window = UIApplication.shared.keyWindow! 
window.addSubview(self.spinnerView) // Add your view here

另一个简单的解决方案是：

yourViewName.layer.zPosition = 1//Here fix your view name

第一种解决方案不考虑设备旋转。第二种解决方案在出现模态viewcontroller时不起作用。第二种用于ipad的解决方案工作得很好，谢谢：）这是一个很大的假设。
let window = UIApplication.shared.keyWindow! 
window.addSubview(self.spinnerView) // Add your view here

yourViewName.layer.zPosition = 1//Here fix your view name