使用 UIAlertController 在 UIImagePicker 中“应用程序试图以模态方式呈现活动控制器”

Posted 2023-03-16

【中文标题】使用 UIAlertController 在 UIImagePicker 中“应用程序试图以模态方式呈现活动控制器”

【英文标题】："Application tried to present modally an active controller" in UIImagePicker with UIAlertController

【发布时间】：2015-12-03 16:04:02

【问题描述】：

在我的应用程序中，我希望用户在拍照时尽可能保持 iphone 水平平坦，因此我想在倾斜度太差时显示警报：

@IBAction func takeSnapshot(sender: UIButton) 
    self.imagePicker =  UIImagePickerController()
    self.imagePicker.delegate = self
    self.imagePicker.sourceType = .Camera
    self.startMotionManager()
    presentViewController(imagePicker, animated: true, completion: nil)


func startMotionManager() 

    let alertController = UIAlertController(title: "Attenzione!", message: "Mantieni l'iphone il più orizzontale possibile!", preferredStyle: .Alert)

    var showAlert:Bool = false

    self.motionManager.deviceMotionUpdateInterval = 0.01
    self.motionManager.startDeviceMotionUpdatesUsingReferenceFrame(CMAttitudeReferenceFrame.XArbitraryZVertical, toQueue: NSOperationQueue.currentQueue()!, withHandler:
        deviceManager, error in
        print(deviceManager?.gravity)
        /* se inclino troppo o troppo poco l'iphone */
        if ((deviceManager?.gravity.z >= -0.999) && (deviceManager?.gravity.z <= -0.980)) 
            if ((!alertController.isViewLoaded()) || (alertController.view.window == nil)) 
                self.imagePicker.presentViewController(alertController, animated: true, completion: nil)
            
        
        /* se l'iphone è inclinato bene allora nascondo l'alert */
        else 
            if ((alertController.view.window != nil) || (alertController.isViewLoaded())) 
                alertController.dismissViewControllerAnimated(true, completion: nil)
            
        
    )

有时，无论是在用户拍照时，还是在刚开始时，我都会收到此错误：

Terminating app due to uncaught exception 'NSInvalidArgumentException', reason: 'Application tried to present modally an active controller <UIImagePickerController: 0x168ec800>.'

我也尝试过一些更简单的方法，例如：

func startMotionManager() 

    let alertController = UIAlertController(title: "Attenzione!", message: "Mantieni l'iphone il più orizzontale possibile!", preferredStyle: .Alert)

    var showAlert:Bool = false

    self.motionManager.deviceMotionUpdateInterval = 0.01
    self.motionManager.startDeviceMotionUpdatesUsingReferenceFrame(CMAttitudeReferenceFrame.XArbitraryZVertical, toQueue: NSOperationQueue.currentQueue()!, withHandler:
        deviceManager, error in
        print(deviceManager?.gravity)
        /* se inclino troppo o troppo poco l'iphone */
        if ((deviceManager?.gravity.z >= -0.999) && (deviceManager?.gravity.z <= -0.980)) 
            if (!showAlert:Bool) 
                showAlert = true
                self.imagePicker.presentViewController(alertController, animated: true, completion: nil)
            
        
        /* se l'iphone è inclinato bene allora nascondo l'alert */
        else 
            if (showAlert) 
                showAlert = false
                alertController.dismissViewControllerAnimated(true, completion: nil)
            
        
    )

但它也不起作用。我在 SO 中阅读了许多关于此的讨论并尝试了其他配置，但它们不起作用。 我该如何解决？

【参考方案1】：

尝试替换这一行：

presentViewController(imagePicker, animated: true, completion: nil)

有了这个

self.navigationController?.pushViewController(imagePicker, animated: YES)

【讨论】：

感谢您的回复，但恐怕不行。现在图像选择器将不再启动...