用于共享屏幕截图的活动控制器显示为空

Question

我希望我的代码在点击名为share的按钮时共享屏幕截图。

按钮功能如下所示：

Swift 3

    func shareBtnAction(_ sender: AnyObject) {

// first I take a screenshot of the drawing    
        UIGraphicsBeginImageContext(drawingAreaView.bounds.size)
        drawingAreaView.image?.draw(in: CGRect(x: 0, y: 0, width: drawingAreaView.frame.size.width, height: drawingAreaView.frame.size.height))

// defining the variable for activityItems  
        let image = UIGraphicsGetImageFromCurrentImageContext()
        UIGraphicsEndImageContext()

// Initialize and present UIActivityViewController         
        let activity = UIActivityViewController(activityItems: [image], applicationActivities: nil)
        present(activity, animated: true, completion: nil)
    }

结果看起来像这样：

当我用文本字符串

替换图像时，我的代码有效

    func shareBtnAction(_ sender: AnyObject) {

// defining the variable for activityItems  
        let text = "This is a test"

// Initialize and present UIActivityViewController         
        let activity = UIActivityViewController(activityItems: [text], applicationActivities: nil)
        present(activity, animated: true, completion: nil)
    }

所以我猜我的代码不能识别图像是UIImage。我只是无法弄清楚原因。

Answer 1

我想， swift 3 希望您更具体地将UIGraphicsGetImageFromCurrentImageContext初始化为UIImage类型：

let image: UIImage = UIGraphicsGetImageFromCurrentImageContext()!

或者在Swift 4中：

let image = UIGraphicsGetImageFromCurrentImageContext() as Any