Question

如何调用这样的函数？

func calculateAndApplyPageHeight() {
    var height : CGFloat = 0
    for v in self.pageView.subviews {
        height += v.frame.height
    }
    print("Height = \(height)!")
    height = height + 40
    if height != self.pageViewHeightConstraint.constant {
        self.pageViewHeightConstraint.constant = height
        self.view.setNeedsDisplay()
    }
}
@IBAction func showSelectedView(_ sender: UISegmentedControl) {

    switch sender.selectedSegmentIndex
    {
    case 0:
        view1.isHidden = false
        view2.isHidden = true
    case 1:
        view1.isHidden = true
        view2.isHidden = false

    default:
        break
    }
    calculateAndApplyPageHeight()
}

这是我的代码

func addWatermark(inputURL: URL, outputURL: URL, handler:@escaping (_ exportSession: AVAssetExportSession?)-> Void) {

    }

无法将类型'（（）-> Void）.Type'的值转换为预期参数输入'（（AVAssetExportSession？）->无效'

Answer 1

首先，在Swift 3+中不要使用SimpleDateFormat dateFormat1 = new SimpleDateFormat("ddMMyyyy"); Date date1 = new Date(); LocalDate date = DateTimeFormat.forPattern("ddMMyyyy").parseLocalDate(dateFormat1.format(date1)); System.out.println("Century=" + date.getCenturyOfEra()); String usFormat = DateTimeFormat.forPattern("ccyy/MM/dd").print(date); System.out.println(usFormat);。使用本机NSURL，这可以避免丑陋的桥式转换。

调用该函数的语法应该看起来像

URL

addWatermark(inputURL: videoURL!, outputURL: videoURL) { exportSession in }是传递的exportSession参数

Answer 2

尝试这样的结尾闭包：

addWatermark(inputURL: videoURL! as URL, outputURL: videoURL! as URL) { exportSession in 

}

或更详细的选择：

addWatermark(inputURL: videoURL, outputURL: videoURL, handler: { exportSession in

})

Answer 3

打电话给你这个功能：

<ListView ItemsSource="{Binding PickingParts}"
          SeparatorVisibility="None"
          SeparatorColor="Transparent"
          RowHeight="100"
          SelectedItem="{Binding SelectedPickingPart, Mode=TwoWay}">

    <ListView.ItemTemplate>
        <DataTemplate>
            <ViewCell>
                <local:PickingPartItemTemplate />
            </ViewCell>
        </DataTemplate>
    </ListView.ItemTemplate>

</ListView>

如何通过参数调用函数

3 个答案: