Question

我正在编写一个代码，允许绘制并将其保存到照片库中，但是当我点击“共享”按钮时，我总是会收到此错误：

Terminating app due to uncaught exception 'NSGenericException', reason:
 'UIPopoverPresentationController (<_UIAlertControllerActionSheetRegularPresentationController: 0x7ff278e533e0>) should have a non-nil sourceView or barButtonItem set before the presentation occurs.'

我已阅读其他问题，但我不明白如何修复它，这是我的代码：

Import UIKit

class SignatureController: UIViewController {

@IBOutlet weak var mainImageView: UIImageView!
@IBOutlet weak var tempImageView: UIImageView!

var lastPoint = CGPoint.zero
var red: CGFloat = 0.0
var green: CGFloat = 0.0
var blue: CGFloat = 0.0
var brushWidth: CGFloat = 10.0
var opacity: CGFloat = 1.0
var swiped = false

let colors: [(CGFloat, CGFloat, CGFloat)] = [
    (0, 0, 0),
    (105.0 / 255.0, 105.0 / 255.0, 105.0 / 255.0),
    (1.0, 0, 0),
    (0, 0, 1.0),
    (51.0 / 255.0, 204.0 / 255.0, 1.0),
    (102.0 / 255.0, 204.0 / 255.0, 0),
    (102.0 / 255.0, 1.0, 0),
    (160.0 / 255.0, 82.0 / 255.0, 45.0 / 255.0),
    (1.0, 102.0 / 255.0, 0),
    (1.0, 1.0, 0),
    (1.0, 1.0, 1.0),
]

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

override func didReceiveMemoryWarning() {
    super.didReceiveMemoryWarning()
    // Dispose of any resources that can be recreated.
}

// MARK: - Actions

@IBAction func reset(sender: AnyObject) {
    mainImageView.image = nil
}

@IBAction func share(sender: AnyObject) {
    UIGraphicsBeginImageContext(mainImageView.bounds.size)
    mainImageView.image?.drawInRect(CGRect(x: 0, y: 0,
        width: mainImageView.frame.size.width, height: mainImageView.frame.size.height))
    let image = UIGraphicsGetImageFromCurrentImageContext()
    UIGraphicsEndImageContext()

    let activity = UIActivityViewController(activityItems: [image], applicationActivities: nil)
    presentViewController(activity, animated: true, completion: nil)
}

@IBAction func pencilPressed(sender: AnyObject) {

    var index = sender.tag ?? 0
    if index < 0 || index >= colors.count {
        index = 0
    }

    (red, green, blue) = colors[index]

    if index == colors.count - 1 {
        opacity = 1.0
    }
}

override func touchesBegan(touches: Set<UITouch>, withEvent event: UIEvent?) {
    swiped = false
    if let touch = touches.first as? UITouch! {
        lastPoint = touch.locationInView(self.view)
    }
}

func drawLineFrom(fromPoint: CGPoint, toPoint: CGPoint) {

    // 1
    UIGraphicsBeginImageContext(view.frame.size)
    let context = UIGraphicsGetCurrentContext()
    tempImageView.image?.drawInRect(CGRect(x: 0, y: 0, width: view.frame.size.width, height: view.frame.size.height))

    // 2
    CGContextMoveToPoint(context, fromPoint.x, fromPoint.y)
    CGContextAddLineToPoint(context, toPoint.x, toPoint.y)

    // 3
    CGContextSetLineCap(context, CGLineCap.Round)
    CGContextSetLineWidth(context, brushWidth)
    CGContextSetRGBStrokeColor(context, red, green, blue, 1.0)
    CGContextSetBlendMode(context, CGBlendMode.Normal)

    // 4
    CGContextStrokePath(context)

    // 5
    tempImageView.image = UIGraphicsGetImageFromCurrentImageContext()
    tempImageView.alpha = opacity
    UIGraphicsEndImageContext()

}

override func touchesMoved(touches: Set<UITouch>, withEvent event: UIEvent?) {
    // 6
    swiped = true
    if let touch = touches.first as? UITouch! {
        let currentPoint = touch.locationInView(view)
        drawLineFrom(lastPoint, toPoint: currentPoint)

        // 7
        lastPoint = currentPoint
    }
}

override func touchesEnded(touches: Set<UITouch>, withEvent event: UIEvent?) {

    if !swiped {
        // draw a single point
        drawLineFrom(lastPoint, toPoint: lastPoint)
    }

    // Merge tempImageView into mainImageView
    UIGraphicsBeginImageContext(mainImageView.frame.size)
    mainImageView.image?.drawInRect(CGRect(x: 0, y: 0, width: view.frame.size.width, height: view.frame.size.height), blendMode: CGBlendMode.Normal, alpha: 1.0)
    tempImageView.image?.drawInRect(CGRect(x: 0, y: 0, width: view.frame.size.width, height: view.frame.size.height), blendMode: CGBlendMode.Normal, alpha: opacity)
    mainImageView.image = UIGraphicsGetImageFromCurrentImageContext()
    UIGraphicsEndImageContext()

    tempImageView.image = nil
}
}

真的感谢您的帮助

Answer 1

您是否正在使用iPad编译代码？我问，因为这是iPad中活动视图控制器的常见错误

在iPad上，活动视图控制器将使用新的UIPopoverPresentationController显示为弹出窗口，因此，您应该在代码中解决它

如何正确设置示例：

if ( [activityViewController respondsToSelector:@selector(popoverPresentationController)] ) { 
     activityViewController.popoverPresentationController.sourceView = parentView
}

我希望这有助于你

Answer 2

UIPopoverPresentationController（＆lt; _UIAlertControllerActionSheetRegularPresentationController：0x7ff278e533e0＆gt;）应该在演示文稿发生之前设置一个非零的sourceView或barButtonItem .-表示您没有设置应该呈现UIImagePickerController的源视图。您还可以设置应从中显示弹出框的矩形。下面的代码位于视图控制器中。

试试此代码

let imagePicker = UIImagePickerController()
    imagePicker.delegate = self
    imagePicker.allowsEditing = false
    let actionsheet:UIAlertController = UIAlertController(title: "", message: nil, preferredStyle: UIAlertControllerStyle.ActionSheet)
    let popper = imagePicker.popoverPresentationController
    popper?.delegate  = self
    popper?.sourceView = self.view
    popper?.sourceRect = CGRectMake(self.view.bounds.width / 2.0 , self.view.bounds.height / 2.0, 1.0, 1.0)
    actionsheet.popoverPresentationController?.sourceView = self.view
    actionsheet.popoverPresentationController?.sourceRect = CGRectMake(self.view.bounds.width / 2.0 , self.view.bounds.height / 2.0, 1.0, 1.0)

    self.presentViewController(actionsheet, animated: true, completion: nil)

尝试共享绘图时出错

2 个答案: