Question

我有一个将多个图像上传到Firebase的项目，并制作了一个常数来计算当前上传进度的百分比：

uploadTask.observe(.progress, handler: { (snapshot) in
                guard let progress = snapshot.progress else {
                    return
                }

                let percentage = (Float(progress.completedUnitCount) / Float(progress.totalUnitCount))
                progressBlock(Double(percentage))
            })

我制作了一个UIView元素，但尚未连接它。我正在尝试使UIView充当进度条，以便用户可见地查看上传进度。我一直在尝试这样做，但是没有成功。我怎样才能做到这一点？顺便说一句：UIView应该随着percentage的增加而增加，并且100％时，UIView将重置并隐藏。

非常感谢您！

Answer 1

创建UIView的自定义子类。为自定义子类赋予属性percentComplete。

让视图使用CAShapeLayer绘制一个填充区域，该区域会随着百分比值从0.0增加到1.0而扩展以填充视图。（您也可以覆盖drawRect()方法并使用Quartz绘图，但是形状图层更容易且性能更高。

在CAShapeLayer上进行一些搜索，以获取有关操作方法的想法。

您可以让视图在视图上添加形状层作为附加层，也可以让视图提供layerClass属性，使视图的内容层成为单个CAShapeLayer

Answer 2

这是用于动态更改视图宽度的代码。

import UIKit

class ViewController: UIViewController {


    var widthAnchor:NSLayoutConstraint!
    let perecentageView:UIView={
        let view = UIView()
        view.backgroundColor = .red
        view.translatesAutoresizingMaskIntoConstraints = false//Its needed becasue we are using anchors
        return view
    }()

    override func viewDidLoad() {
        super.viewDidLoad()

        self.view.addSubview(perecentageView)
        perecentageView.topAnchor.constraint(equalTo: self.view.topAnchor, constant: 100).isActive = true
        perecentageView.leftAnchor.constraint(equalTo: self.view.leftAnchor, constant: 10).isActive = true
        perecentageView.heightAnchor.constraint(equalToConstant: 50).isActive = true
        widthAnchor = perecentageView.widthAnchor.constraint(equalToConstant: 0) // By default its 0
        widthAnchor.isActive = true

        self.uploadProgess()

    }


    func uploadProgess(){
        uploadTask.observe(.progress, handler: { (snapshot) in
            guard let progress = snapshot.progress else {
                return
            }

            let percentage = (Float(progress.completedUnitCount) / Float(progress.totalUnitCount))


            let newWidth = self.view.frame.width * percentage / 100
            DispatchQueue.main.async(execute: {
                self.widthAnchor.constant = newWidth
               // self.view.frame.width is the parent view (And max width will be = self.view.frame.width)
               //if you are using view from storybard with aoutolayout then just take IBOutlet of view's with and here widthAnchor = your IBOutlet

                /*
                 if you are using view from storybard and without autolayout then use below code
                 self.perecentageView.frame = CGRect(x: self.perecentageView.frame.origin.x, y: self.perecentageView.frame.origin.y, width: newWidth, height: self.perecentageView.frame.height)
                 */
            })


        })
    }


}

当上传百分比增加时，如何使UIView的宽度增加？ SWIFT 4

2 个答案: