UIProgressView setProgress问题

Question

我在使用UIProgressView时遇到了问题，低值（1％-大约10％）看起来很低。您可以在上面的示例中看到97％看起来准确，而2％看起来不准确。

以下是设置颜色的代码：

self.progressView.trackTintColor = UIColor.green.withAlphaComponent(0.3)
self.progressView.tintColor = UIColor.green.withAlphaComponent(1.0)

但是，如果我注释掉trackTintColor或tintColor，则2％看起来是正确的。为什么将它们一起使用会导致此问题？只是一个Xcode错误？有人解决过吗？

Answer 1

您需要创建彩色图像
SWIFT 3示例：

class ViewController: UIViewController {

    @IBOutlet weak var progressView: UIProgressView!   

    @IBAction func lessButton(_ sender: UIButton) {
        let percentage  = 20
        let invertedValue = Float(100 - percentage) / 100
        progressView.setProgress(invertedValue, animated: true)
    }

    @IBAction func moreButton(_ sender: UIButton) {
        let percentage  = 80
        let invertedValue = Float(100 - percentage) / 100
        progressView.setProgress(invertedValue, animated: true)
    }

    override func viewDidLoad() {
        super.viewDidLoad()

        //create gradient view the size of the progress view
        let gradientView = GradientView(frame: progressView.bounds)

        //convert gradient view to image , flip horizontally and assign as the track image
        progressView.trackImage = UIImage(view: gradientView).withHorizontallyFlippedOrientation()

        //invert the progress view
        progressView.transform = CGAffineTransform(scaleX: -1.0, y: -1.0)

        progressView.progressTintColor = UIColor.black
        progressView.progress = 1

    }

}

extension UIImage{
    convenience init(view: UIView) {

        UIGraphicsBeginImageContext(view.frame.size)
        view.layer.render(in: UIGraphicsGetCurrentContext()!)
        let image = UIGraphicsGetImageFromCurrentImageContext()
        UIGraphicsEndImageContext()
        self.init(cgImage: (image?.cgImage)!)

    }
}

@IBDesignable
class GradientView: UIView {

    private var gradientLayer = CAGradientLayer()
    private var vertical: Bool = false

    override func draw(_ rect: CGRect) {
        super.draw(rect)
        // Drawing code

        //fill view with gradient layer
        gradientLayer.frame = self.bounds

        //style and insert layer if not already inserted
        if gradientLayer.superlayer == nil {

            gradientLayer.startPoint = CGPoint(x: 0, y: 0)
            gradientLayer.endPoint = vertical ? CGPoint(x: 0, y: 1) : CGPoint(x: 1, y: 0)
            gradientLayer.colors = [UIColor.green.cgColor, UIColor.red.cgColor]
            gradientLayer.locations = [0.0, 1.0]

            self.layer.insertSublayer(gradientLayer, at: 0)
        }
    }

}

Answer 2

我在项目中遇到了同样的问题。对我来说，它是通过使用progressTintColor而不是tintColor来解决的。

progressView.progressTintColor = UIColor.green.withAlphaComponent(1.0)
progressView.trackTintColor = UIColor.green.withAlphaComponent(0.3)